Race condition fix.

Fixes a clang warning.

libwrap support is in MPD but only for the control port.  This patch
adds support for the http port.  The code is copied from
src/client_new.c

Print those files which can be handled by a playlist plugin.

Memory leak fix.  The input_stream object passed to
playlist_list_open_stream_suffix() must be closed by the caller - this
however never happens in playlist_list_open_path(), because it does
not return it to the caller.

There is no useful return value here.

The return value of Player_LoadTitle() is allocated with malloc(), and
must be freed by the caller.

Added macros with better names: GME_BUFFER_FRAMES, GME_BUFFER_SAMPLES
(the former only used to calculate the latter).

Move into enums.

Pass sizeof(buf) to decoder_data(), not the number of samples (which
is half the size).  At the same time, pass GME_BUF_SIZE to gme_play()
- libgme really wants to get the number of samples, not the number of
stereo frames.  Previously, this plugin had been using only the first
half of the buffer.

Allocate the "tag" object after the file has been opened successfully.

Allocate the "tag" object after the file has been checked.  That
removes one tag_free() call in an error handler.

Allocate only one item on the stack.

Reuse the function tag_name_parse_i().

Reuse the function tag_name_parse_i().

This allows tags in archive files.

Initialize the ov_callbacks struct at compile time.

This is probably unsafe, and doesn't protect against symlink loops,
but we will eventually add this when we bring update*.c and inotify*.c
closer together.

This shouldn't really happen, but insane users might delete/rename the
music directory while MPD runs.  What was even more insane was that
MPD crashed due to this.  This is a workaround - there is currently
nothing useful we can do in this case; except maybe poll for the music
directory to reappear, but that's too much trouble for a user error.

I'm not sure if mapping "band" to TAG_PERFORMER is correct, but it
might be better than nothing.

Convert if/else/else/... to a loop.

The underlying library is named "libmp4ff".  To reduce confusion,
rename the plugin to a more specific name.