Relative timestamps in git log

Relative timestamps in git log

I noticed that I was looking at the kernel gitweb output at some point
rather than just do "git log", simply because I liked seeing the
simplified date-format, ie the "5 days ago" rather than a full date.

This adds infrastructure to do that for "git log" too. It does NOT add the
actual flag to enable it, though, so right now this patch is a no-op, but
it should now be easy to add a command line flag (and possibly a config
file option) to just turn on the "relative" date format.

The exact cut-off points when it switches from days to weeks etc are
totally arbitrary, but are picked somewhat to avoid the "1 weeks ago"
thing (by making it show "10 days ago" rather than "1 week", or "70
minutes ago" rather than "1 hour ago").

[jc: with minor fix and tweak around "month" and "week" area.]

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>