This is where loose content objects are stored as one compressed file,
instead of the two separate ones for regular archive mode. This mode
would be suitable for HTTP servers, beause only one HTTP request is
necessary, and the result would be compressed.
Since we're making a shared library, it should be usable by non-GPL
apps.
To allow more code sharing between the core and the tests, move them
to the LGPLv2+ too.
A few bits of test and other code are still GPL. See the new COPYING
file for more information.