[PATCH] Initial import of git-archimport-script

Imports a project history from one or more Arch repositories, following
the branching and tagging across repositories. Note you should import
separate projects to separate GIT repositories.

Supported
 - Imports, tags and simple commits.
 - File renames
 - Arch tags
 - Binary files
 - Large trees
 - Multiple repositories
 - Branches

TODO:
 - Allow re-running the import on an already-imported project
 - Follow merges using Arch data
 - Audit shell escaping of filenames
 - Better support for file metadata
 - Better/safer creation of temp directories

Unsupported:
 - Arch 'configuration'

[jc: my arch/tla is very rusty and after Tom announced he is stepping
 down as the maintainer I have very little motivation to relearn it,
 so I would appreciate if people discuss any bugs or enhancements
 directly with Martin.  Of course I can help with the git end of the
 issues.]

Signed-off-by: Martin Langhoff <martin@catalyst.net.nz>
Signed-off-by: Junio C Hamano <junkio@cox.net>