gitweb: Add author initials in 'blame' view, a la "git gui blame"

For example for "Junio C Hamano" initials would be "JH".  Of course
initials are added (below shortened SHA-1 of blamed commit) only if
group of lines that blame the same commit has 2 or more lines in it.

Initials are extracted using i18n /\b([[:upper:]])\B/g regexp.

Additionally initials help to distinguish boundary commits, as they
use bold weight font too (in addition to shortened SHA-1 of commit).

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -4855,6 +4855,14 @@ sub git_blame {
 			                             hash=>$full_rev,
 			                             file_name=>$file_name)},
 			              esc_html($short_rev));
+			if ($group_size >= 2) {
+				my @author_initials = ($author =~ /\b([[:upper:]])\B/g);
+				if (@author_initials) {
+					print "<br />" .
+					      esc_html(join('', @author_initials));
+					#           or join('.', ...)
+				}
+			}
 			print "</td>\n";
 		}
 		# 'previous' <sha1 of parent commit> <filename at commit>