Document manifest fields better
Fix iseq for null strings
Parameterise type of hash used
Add ./install.sh to install git-remote-gcrypt and its man page
Simplify informational output to emphasize the new repo URL
Repack the encrypted remote regularly

Use a simple but slow method of repacking the remote repository.
Download (and verify) all packs not marked 'keep', and repack those into
a new packfile. The new packfile is marked 'keep' with generation 1.
After PUT is called on the manifest, we remove the redundant old
packfiles.

The generation number will allow further iterations of repacking to be
implemented later.
Document the keep field
Use rsync for both rsync and ssh access
Use normal "url-safe" variant of base64 for repo url fragment
Factor out common code in do_fetch and repack
Unify all uses of trap
Allow user to set $GCRYPT_FULL_REPACK to force repack of remote
Give warning about future format change