Sourcecode of modified 3. party libs

[Martin Gysel]

Hi Dirk

What do you think about archiving the modified 3rd party libs for each
subsurface release (e.g. in a separate tar Subsurface-bundle.tgz)?
Otherwise it's not so trivial to know what lib has been used in which
version to build the official release binary. It would also help
packaging it for distros where shipping bundles libs is possible.

Thanks
martin