[twin-font] Clean up font data by joining lines and closing paths

Two changes here:

  * Replace move_to;line_to;move_to;line_to sequences with
    move_to;line_to;line_to when feasible.

  * Close paths for round glyphs.

Both improve the stroke rendering of the joint.

The first change also saves 3 bytes per joint (33 such joints).
Which we have just left unused for now.  To reclaim them one need
to update the charset table.  Something for a lazy Sunday afternoon
scripting task.

In the saving department, we can save further by:

  - Getting rid of the left/ascent/descent values as we compute
    glyph bounding box automatically.  Then we can liberally use
    the right value to adjust glyph advance width.  Saves three
    bytes per glyph (there's 96 glyphs in the font).

  - First operation is always a move_to.  So we can remove the 'm'
    for that.  Ugly though.

And the charset has zeros for the first 32 entries.  Can get rid of
that too at the expense of handling it in the code...

In total, combining the above we can save some 500 bytes.  The font
currently takes about 3.7kb.

src/cairo-font-face-twin-data.c

@@ -72,22 +72,22 @@ const int8_t _cairo_twin_outlines[] = {
     0, 36, 42, 0, 4, 7,
     0, 14, 22, 36, /* snap_x */
     -42, -38, -28, -21, -15, -14, 0, /* snap_y */
-    'm', 36, -42,
-    'l', 0, 0,
     'm', 10, -42,
     'c', 12, -41, 14, -40, 14, -36,
     'c', 14, -30, 11, -28, 6, -28,
     'c', 2, -28, 0, -30, 0, -34,
     'c', 0, -39, 3, -42, 8, -42,
     'l', 10, -42,
     'c', 18, -37, 28, -37, 36, -42,
+    'l', 0, 0,
     'm', 28, -14,
     'c', 24, -14, 22, -11, 22, -6,
     'c', 22, -2, 24, 0, 28, 0,
     'c', 33, 0, 36, -2, 36, -8,
     'c', 36, -12, 34, -14, 30, -14,
     'l', 28, -14,
     'e',
+    'X', 'X', 'X',
 /* 0x26 '&'  offset 323 */
     0, 40, 42, 0, 4, 4,
     0, 10, 22, 40, /* snap_x */
@@ -183,7 +183,7 @@ const int8_t _cairo_twin_outlines[] = {
     'c', 0, 0, 9, 0, 14, 0,
     'c', 19, 0, 28, 0, 28, -21,
     'c', 28, -42, 19, -42, 14, -42,
-    'e',
+    'E',
 /* 0x31 '1'  offset 666 */
     0, 28, 42, 0, 2, 3,
     0, 17, 28 /* snap_x */
@@ -218,12 +218,12 @@ const int8_t _cairo_twin_outlines[] = {
     0, 28, 42, 0, 3, 4,
     0, 20, 30, /* snap_x */
     -21, -15, -14, 0, /* snap_y */
-    'm', 20, -42,
+    'm', 20, 0,
+    'l', 20, -42,
     'l', 0, -14,
     'l', 30, -14,
-    'm', 20, -42,
-    'l', 20, 0,
     'e',
+    'X', 'X', 'X',
 /* 0x35 '5'  offset 809 */
     0, 28, 42, 0, 2, 5,
     0, 28, /* snap_x */
@@ -252,11 +252,11 @@ const int8_t _cairo_twin_outlines[] = {
     0, 28, 42, 0, 2, 4,
     0, 28, /* snap_x */
     -42, -21, -15, 0, /* snap_y */
-    'm', 28, -42,
-    'l', 8, 0,
     'm', 0, -42,
     'l', 28, -42,
+    'l', 8, 0,
     'e',
+    'X', 'X', 'X',
 /* 0x38 '8'  offset 944 */
     0, 28, 42, 0, 4, 4,
     0, 2, 26, 28, /* snap_x */
@@ -268,7 +268,7 @@ const int8_t _cairo_twin_outlines[] = {
     'c', 10, 0, 0, 0, 0, -11,
     'c', 0, -32, 26, -18, 26, -34,
     'c', 26, -40, 23, -42, 14, -42,
-    'e',
+    'E',
 /* 0x39 '9'  offset 1004 */
     0, 28, 42, 0, 2, 5,
     0, 26, /* snap_x */
@@ -362,27 +362,27 @@ const int8_t _cairo_twin_outlines[] = {
     0, 32, 42, 0, 2, 4,
     0, 32, /* snap_x */
     -21, -15, -14, 0, /* snap_y */
-    'm', 16, -42,
-    'l', 0, 0,
-    'm', 16, -42,
+    'm', 0, 0,
+    'l', 16, -42,
     'l', 32, 0,
     'm', 6, -14,
     'l', 26, -14,
     'e',
+    'X', 'X', 'X',
 /* 0x42 'B'  offset 1406 */
     0, 28, 42, 0, 2, 5,
     0, 28, /* snap_x */
     -42, -22, -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 18, -42,
     'c', 32, -42, 32, -22, 18, -22,
-    'm', 0, -22,
+    'l', 0, -22,
     'l', 18, -22,
     'c', 32, -22, 32, 0, 18, 0,
-    'l', 0, 0,
-    'e',
+    'E',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x43 'C'  offset 1455 */
     0, 30, 42, 0, 2, 4,
     0, 30, /* snap_x */
@@ -397,37 +397,37 @@ const int8_t _cairo_twin_outlines[] = {
     0, 28, 42, 0, 2, 4,
     0, 28, /* snap_x */
     -42, -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 14, -42,
     'c', 33, -42, 33, 0, 14, 0,
-    'l', 0, 0,
-    'e',
+    'E',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x45 'E'  offset 1534 */
     0, 26, 42, 0, 2, 5,
     0, 26, /* snap_x */
     -42, -22, -21, -15, 0, /* snap_y */
-    'm', 0, -42,
+    'm', 26, -42,
+    'l', 0, -42,
     'l', 0, 0,
-    'm', 0, -42,
-    'l', 26, -42,
+    'l', 26, 0,
     'm', 0, -22,
     'l', 16, -22,
-    'm', 0, 0,
-    'l', 26, 0,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x46 'F'  offset 1572 */
     0, 26, 42, 0, 2, 5,
     0, 26, /* snap_x */
     -42, -22, -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 26, -42,
     'm', 0, -22,
     'l', 16, -22,
     'e',
+    'X', 'X', 'X',
 /* 0x47 'G'  offset 1604 */
     0, 30, 42, 0, 2, 5,
     0, 30, /* snap_x */
@@ -437,9 +437,9 @@ const int8_t _cairo_twin_outlines[] = {
     'c', 2, -42, 0, -29, 0, -21,
     'c', 0, -13, 2, 0, 16, 0,
     'c', 28, 0, 30, -7, 30, -16,
-    'm', 20, -16,
-    'l', 30, -16,
+    'l', 20, -16,
     'e',
+    'X', 'X', 'X',
 /* 0x48 'H'  offset 1655 */
     0, 28, 42, 0, 2, 4,
     0, 28, /* snap_x */
@@ -484,33 +484,33 @@ const int8_t _cairo_twin_outlines[] = {
     -21, -15, 0, /* snap_y */
     'm', 0, -42,
     'l', 0, 0,
-    'm', 0, 0,
     'l', 24, 0,
     'e',
+    'X', 'X', 'X',
 /* 0x4d 'M'  offset 1785 */
     0, 32, 42, 0, 2, 3,
     0, 32, /* snap_x */
     -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
-    'l', 16, 0,
-    'm', 32, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 16, 0,
-    'm', 32, -42,
+    'l', 32, -42,
     'l', 32, 0,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x4e 'N'  offset 1821 */
     0, 28, 42, 0, 2, 3,
     0, 28, /* snap_x */
     -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
-    'l', 28, 0,
-    'm', 28, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 28, 0,
+    'l', 28, -42,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x4f 'O'  offset 1851 */
     0, 32, 42, 0, 2, 4,
     0, 32, /* snap_x */
@@ -520,18 +520,18 @@ const int8_t _cairo_twin_outlines[] = {
     'c', 0, -13, 2, 0, 16, 0,
     'c', 30, 0, 32, -13, 32, -21,
     'c', 32, -29, 30, -42, 16, -42,
-    'e',
+    'E',
 /* 0x50 'P'  offset 1895 */
     0, 28, 42, 0, 2, 5,
     0, 28, /* snap_x */
     -42, -21, -20, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 18, -42,
     'c', 32, -42, 32, -20, 18, -20,
     'l', 0, -20,
     'e',
+    'X', 'X', 'X',
 /* 0x51 'Q'  offset 1931 */
     0, 32, 42, 4, 2, 4,
     0, 32, /* snap_x */
@@ -548,15 +548,15 @@ const int8_t _cairo_twin_outlines[] = {
     0, 28, 42, 0, 2, 5,
     0, 28, /* snap_x */
     -42, -22, -21, -15, 0, /* snap_y */
-    'm', 0, -42,
-    'l', 0, 0,
-    'm', 0, -42,
+    'm', 0, 0,
+    'l', 0, -42,
     'l', 18, -42,
     'c', 32, -42, 31, -22, 18, -22,
     'l', 0, -22,
     'm', 14, -22,
     'l', 28, 0,
     'e',
+    'X', 'X', 'X',
 /* 0x53 'S'  offset 2023 */
     0, 28, 42, 0, 2, 4,
     0, 28, /* snap_x */
@@ -592,22 +592,22 @@ const int8_t _cairo_twin_outlines[] = {
     -21, -15, 0, /* snap_y */
     'm', 0, -42,
     'l', 16, 0,
-    'm', 32, -42,
-    'l', 16, 0,
+    'l', 32, -42,
     'e',
+    'X', 'X', 'X',
 /* 0x57 'W'  offset 2152 */
     0, 40, 42, 0, 2, 3,
     0, 40, /* snap_x */
     -21, -15, 0, /* snap_y */
     'm', 0, -42,
     'l', 10, 0,
-    'm', 20, -42,
-    'l', 10, 0,
-    'm', 20, -42,
-    'l', 30, 0,
-    'm', 40, -42,
+    'l', 20, -42,
     'l', 30, 0,
+    'l', 40, -42,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x58 'X'  offset 2188 */
     0, 28, 42, 0, 2, 3,
     0, 28, /* snap_x */
@@ -631,13 +631,13 @@ const int8_t _cairo_twin_outlines[] = {
     0, 28, 42, 0, 2, 4,
     0, 28, /* snap_x */
     -42, -21, -15, 0, /* snap_y */
-    'm', 28, -42,
+    'm', 28, 0,
     'l', 0, 0,
-    'm', 0, -42,
     'l', 28, -42,
-    'm', 0, 0,
-    'l', 28, 0,
+    'l', 0, -42,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x5b '['  offset 2271 */
     0, 14, 44, 0, 2, 4,
     0, 14, /* snap_x */
@@ -667,11 +667,11 @@ const int8_t _cairo_twin_outlines[] = {
     0, 32, 46, -18, 2, 3,
     0, 32, /* snap_x */
     -21, -15, 0, /* snap_y */
-    'm', 16, -46,
-    'l', 0, -18,
-    'm', 16, -46,
+    'm', 0, -18,
+    'l', 16, -46,
     'l', 32, -18,
     'e',
+    'X', 'X', 'X',
 /* 0x5f '_'  offset 2363 */
     0, 36, 0, 0, 2, 3,
     0, 36, /* snap_x */
@@ -921,22 +921,22 @@ const int8_t _cairo_twin_outlines[] = {
     -21, -15, 0, /* snap_y */
     'm', 0, -28,
     'l', 12, 0,
-    'm', 24, -28,
-    'l', 12, 0,
+    'l', 24, -28,
     'e',
+    'X', 'X', 'X',
 /* 0x77 'w'  offset 3307 */
     0, 32, 28, 0, 2, 3,
     0, 32, /* snap_x */
     -21, -15, 0, /* snap_y */
     'm', 0, -28,
     'l', 8, 0,
-    'm', 16, -28,
-    'l', 8, 0,
-    'm', 16, -28,
-    'l', 24, 0,
-    'm', 32, -28,
+    'l', 16, -28,
     'l', 24, 0,
+    'l', 32, -28,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x78 'x'  offset 3343 */
     0, 22, 28, 0, 2, 3,
     0, 22, /* snap_x */
@@ -960,13 +960,13 @@ const int8_t _cairo_twin_outlines[] = {
     0, 22, 28, 0, 2, 4,
     0, 22, /* snap_x */
     -28, -21, -15, 0, /* snap_y */
-    'm', 22, -28,
+    'm', 22, 0,
     'l', 0, 0,
-    'm', 0, -28,
     'l', 22, -28,
-    'm', 0, 0,
-    'l', 22, 0,
+    'l', 0, -28,
     'e',
+    'X', 'X', 'X',
+    'X', 'X', 'X',
 /* 0x7b '{'  offset 3430 */
     0, 16, 44, 0, 3, 5,
     0, 6, 16, /* snap_x */