Add a helper to create & initialize GTRepositories in one step
Add spec file for filesystem-less repository manipulation.
Use a GTOID directly.
Dot accessor.
Add GTOID initializers for data + object type.
const-ify arguments.
`stream` isn't freed.
Refactor the streaming write call to be more "general".

If someone gets an epiphany on how to do that without passing the git_odb_stream object to the block or copying the data…
Add a convenience call to create tree entries and their data at the same time.
Convenience call to create commits.
Spec for the easy commit creation.
EOF newline.
This one is the correct one.
Merge branch 'master' into repo-manipulation

Conflicts:
	Classes/GTObjectDatabase.m
	Classes/GTRepository.h
	Classes/GTRepository.m
	Classes/GTTreeBuilder.h
	Classes/GTTreeBuilder.m
Remove the block-based writer and some oft-used methods.
Make `+[GTRepository hash:…]` use the new GTOID hash method.
Merge branch 'master' into repo-manipulation2

Conflicts:
	Classes/GTRepository.h
	Classes/GTRepository.m
Update spec.
More logical commit creation method.
Don't use a temp variable.