a bunch of outstanding updates

[Sam Vilain <sam.vilain@catalyst.net.nz>]

Following up to this e-mail are a whole load of outstanding feature
requests of mine.

These changes are relatively mundane:

    * repack: improve documentation on -a option
    * git-remote: document -n
    * git-remote: allow 'git-remote fetch' as a synonym for 'git fetch'
    * git-svn: use git-log rather than rev-list | xargs cat-file
    * git-svn: cache max revision in rev_db databases

This one will impact on the version displayed by "git --version", but
I think this is for the better:

    * GIT-VERSION-GEN: don't convert - delimiter to .'s

These ones are really only very minor updates based on feedback so
far:

    * git-merge-ff: fast-forward only merge
    * git-mergetool: add support for ediff

This one is just the previously posted hook script put into the
templates directory, let me know if you'd rather I reshaped it to go
into contrib/hooks:

    * contrib/hooks: add post-update hook for updating working copy

This one probably needs a bit more consideration and review, could
perhaps sit on pu.

    * git-repack: generational repacking (and example hook script)