Check if the stream is suspended; wake up the main loop when it
becomes suspended.

Not a bool.

Unlock the mainloop in all code paths.

This warning should only be logged when we really received something.
When the client disconnects, G_IO_IN is triggered, and the read
returns G_IO_STATUS_EOF.

In the "vorbis" plugin, this is a copy of the old flush() method,
while flush() gets a lot of code remove, it just sets the "flush" flag
and nothing else.  It doesn't start a new stream now, which should fix
a few problems in some players.

Fixes build failure on WIN32.

See code comment.

According to the Solaris dsp manpage, AFMT_S24_PACKED is
little-endian:

 http://download.oracle.com/docs/cd/E19963-01/821-1475/6nmf5baot/index.html

The Minix soundcard.h header says the same.

With mono sound, jack_sample_size is smaller than frame_size (4 vs 2
bytes), and "space/jack_sample_size==0".  That means mpd_jack_play()
will return 0, although no error has occurred.

Version 1.0.0 of the libao library added a new field to the
ao_sample_format struct.  It is a char * named matrix.  When
an ao_sample_format is allocated on the stack, this field contains
garbage.  The proper course is to insure that is initialized to NULL.
NULL indicates that we do not want any mapping.
The struct is now initialized using a static initializer, and this
technique is compatible with all known versions of libao.

Remove trailing whitespace found by this command:
find -name '*.[ch]' | xargs grep "[[:space:]]$"

This fixes the following valgrind warning occuring on the first call of
httpd_output_read_page:
==20124== Conditional jump or move depends on uninitialised value(s)
==20124==    at 0x425E65: httpd_output_read_page (httpd_output_plugin.c:240)
==20124==    by 0x426087: httpd_output_open (httpd_output_plugin.c:279)
==20124==    by 0x41D862: ao_open (output_plugin.h:206)
==20124==    by 0x41E133: audio_output_task (output_thread.c:590)

This is a MPD 0.16 regression: when playing a 24 bit file, the switch
to 16 bit was made only partially, after mBytesPerPacket and
mBytesPerFrame had already been applied.

That means mBytesPerFrame referred to 24 bit, and mBitsPerChannel
referred to 16 bits.  Of course, that cannot work.

After popular demand, I've switched the order of "artist" and "title"
in the stream title.  There is no standard, and there is no reliable
way to parse those from the stream title.

This makes the plugin more responsive to control commands, because it
will listen to control events while waiting.

libffado documentation says this function returns -1 on error, but
that is a lie - it returns a boolean value, and "false" means error.

Device can be specified either by magic index (starting with 0)
or by device name.

If no device is available test_default_device returns false.

Using libffado, to play on firewire audio devices.

Warning: this plugin was not tested successfully.  I just couldn't
keep libffado2 from crashing.  Use at your own risk.

For details, see my Debian bug reports:

  http://bugs.debian.org/601657
  http://bugs.debian.org/601659

Win32 has many audio APIs. New name is slightly more correct.

This cleanup call is obsolete, since we moved the binding code to
enable()/disable().

RFC 5334 10.3 defines the MIME type "audio/ogg".  We could use
"application/ogg" as well, but we know for sure that we only emit
audio data.

Replaced all occurrences of g_error() with MPD_ERROR() located in a new header
file 'mpd_error.h'. This macro uses g_critical() to print the error message
and then exits gracefully in contrast to g_error() which would internally call
abort() to produce a core dump.

The macro name is distinctive and allows to find all places with dubious error
handling. The long-term goal is to get rid of MPD_ERROR() altogether. To
facilitate the eventual removal of this macro it was added in a new header
file rather than to an existing header file.

This fixes #2995 and #3007.