git-gui: sort the numeric ansi codes

This ensures that underline does not conflict with inverse colors.
Signed-off-by: NPat Thoyts <patthoyts@users.sourceforge.net>

lib/diff.tcl

@@ -502,7 +502,7 @@ proc read_diff {fd conflict_size cont_info} {
 
 		foreach {posbegin colbegin posend colend} $markup {
 			set prefix clr
-			foreach style [split $colbegin ";"] {
+			foreach style [lsort -integer [split $colbegin ";"]] {
 				if {$style eq "7"} {append prefix i; continue}
 				if {$style != 4 && ($style < 30 || $style > 47)} {continue}
 				set a "$mark linestart + $posbegin chars"