The libmusicbrainz (also known as mb_client or MusicBrainz Client Library) 
is a development library geared towards developers who wish to add 
MusicBrainz lookup capabilities to their applications.

This requires libdiscid, and cppunit is an optional build-time dep.

Note: This is a new library for libmusicbrainz, which is not backwards 
compatible with previous versions.  It is safe to have version 2.X and 
version 3.X on the same system as they don't conflict with each other.
