Conflicts:
	NEWS
	configure.ac
	src/client_file.h

That function is not pure, it writes to error.

When marked as pure, the compiler is allowed to assume it does not do
anything to error, so it can remain NULL, which would result in an
invalid read in print_error().

Rewrite of the pc_get_error_message() function, now using a GError
object instead of the complicated "errored_song" attribute.

Eliminates explicit global initialisation.

The new block overrides the "db_file" setting, and allows configuring
any database plugin.

No more hard-coded "simple" plugin.

Let the caller take care for legacy conversion.

Preparing for non-"simple" database plugins.

Useless call.

Fixes assertion failures in the Directory library.

Implements error checking for the gmtime_r() call, which was missing
in two code locations.

Implementation incomplete, but sort-of-works.  DumpDatabase works, but
MPD is still hard-coded on the "simple" plugin.

Fixes regression.

Let the database plugin do the match.

Merge locate_song_search() and locate_song_match().

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