ported the old index-color mutt patch to mutt-kz
added support for individual tag coloring
added "Tags:" header output in pager showing all tags
added documentation for index object highlighting
ported nested if-else conditional patch to mutt-kz (credit to David Champion <dgc>)
ported date conditional patch to mutt-kz (credit to Aaron Schrab <ats>)
changed date conditional comparisons
now d = yesterday, w = last week, m = last month, y = last year, H = last hour, etc from current time
added some documentation
fixed right alignment on the index line
the printed string width computation did not account for special index coloring sequences
notmuch: clean up tags related code, improve %G

 - clean up code
 - allows to use %G (and transform-tags) for unhidden tags too

Signed-off-by: Karel Zak <kzak@redhat.com>