This code is mainly a POC for delta sync in owncloud. It uses zsync ( http://zsync.moria.org.uk/ ) and is heavily based on that source code.
Beware that this is messy, inefficient and undocumented code!
Use at your own risk.
Currently this is licenend under the The Artistic License Version 2.0beta4 as that is the zsync licence. I still need to find out if this is GPL compatible.