i#1565 patchlevel in git: use the committer date for the patchlevel

Switches from the svn revision to the committer date for the last commit as
the patchlevel in the version number.
Transition to git: developer setup script and git hooks

Adds a developer setup script and git hooks to add aliases and
configurations for our workflow.  A developer should run
make/git/devsetup.sh once in each repository after cloning.

Currently some of these scripts assume that unix utilities are on the
path.  We may need to augment them for better Windows support.