Merge locate_song_search() and locate_song_match().

Fold the case during construction, without having to create another
copy.

Prepare to use the DatabasePlugin C++ API directly.

Prepare for splitting command.c.

Needed by ax_append_link_flags.m4.

Unused.

Allow using the object outside of DatabaseGlue.cxx.

Remove GLib dependency from some headers.

Produce a smaller binary by removing all unused functions.

Soon we'll use C++11 lambdas which were implemented in gcc 4.5.

We'll add some C++11 code soon.

Use standard scripts instead of MPD's custom implementation.