Merge branch 'kn/ref-filter-atom-parsing'

The ref-filter's format-parsing code has been refactored, in
preparation for "branch --format" and friends.

* kn/ref-filter-atom-parsing:
  ref-filter: introduce objectname_atom_parser()
  ref-filter: introduce contents_atom_parser()
  ref-filter: introduce remote_ref_atom_parser()
  ref-filter: align: introduce long-form syntax
  ref-filter: introduce align_atom_parser()
  ref-filter: introduce parse_align_position()
  ref-filter: introduce color_atom_parser()
  ref-filter: introduce parsing functions for each valid atom
  ref-filter: introduce struct used_atom
  ref-filter: bump 'used_atom' and related code to the top
  ref-filter: use string_list_split over strbuf_split

Documentation/git-for-each-ref.txt

@@ -133,14 +133,18 @@ color::
 
 align::
 	Left-, middle-, or right-align the content between
-	%(align:...) and %(end). The "align:" is followed by `<width>`
-	and `<position>` in any order separated by a comma, where the
-	`<position>` is either left, right or middle, default being
-	left and `<width>` is the total length of the content with
-	alignment. If the contents length is more than the width then
-	no alignment is performed. If used with '--quote' everything
-	in between %(align:...) and %(end) is quoted, but if nested
-	then only the topmost level performs quoting.
+	%(align:...) and %(end). The "align:" is followed by
+	`width=<width>` and `position=<position>` in any order
+	separated by a comma, where the `<position>` is either left,
+	right or middle, default being left and `<width>` is the total
+	length of the content with alignment. For brevity, the
+	"width=" and/or "position=" prefixes may be omitted, and bare
+	<width> and <position> used instead.  For instance,
+	`%(align:<width>,<position>)`. If the contents length is more
+	than the width then no alignment is performed. If used with
+	'--quote' everything in between %(align:...) and %(end) is
+	quoted, but if nested then only the topmost level performs
+	quoting.
 
 In addition to the above, for commit and tag objects, the header
 field names (`tree`, `parent`, `object`, `type`, and `tag`) can