This allows us to also actually check the sha1 hash using these routines. Needed for the "fsck" thing.
And fix up the warnings that it pointed out. Let's keep the tree clean from early on. Not that the code is very beautiful anyway ;)
The tool interface sucks (especially "committing" information, which is just me doing everything by hand from the command line), but I think this is in theory actually a viable way of describing the world. So copyright it.
