Fixes build regression.

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.

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

Make it X_decoder_plugin.c.

This function replaces the replay_gain_info parameter for
decoder_data().  This allows the decoder to announce replay gain
changes, instead of having to pass the same object over and over.

Remove the data_time parameter from decoder_data().  This patch
eliminates the timestamp counting in most decoder plugins, because the
MPD core will do it automatically by default.

Removed local variable "sample_rate".

This patch prepares support for floating point samples (and probably
other formats).  It changes the meaning of the "bits" attribute from a
bit count to a symbolic value.

Don't maintain the current time stamp in a floating point variable,
because this is subject to rounding errors.

The new option "sample_rate" sets the sample rate for libmikmod.

These functions are trivial, we don't need them separate.

Don't allocate this object, put it on the stack.

Let the audio_check library verify the audio format in all (relevant,
i.e. non-hardcoded) plugins.

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.

It makes no difference right now, but we're about to add an endianness
flag and will want to make sure it's correctly initialised every time.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

Fixed the log domains of the renamed decoders.  Added G_LOG_DOMAIN
macros in decoders which don't have one already.

Preparing for per-plugin configuration sections in mpd.conf.

Hi -
independently of libmikmod's other problems - there seems
to be a problem in mpd's wrapper: MikMod_Exit() is called
after the first file is decoded, which frees some ressources
within the mikmod library. An attempt to play a second file
leads to a crash. The appended patch fixes this for me.
(I don't know what the "dup" entry is good for - someone
who knows should review that too.)
best regards
Matthias

[mk: removed 3 more MikMod_Exit() invocations]

On some platforms, g_free() must be used for memory allocated by
GLib.  This patch intends to correct a lot of occurrences, but is
probably not complete.

We have two mod plugins now: modplug and mod.  Rename the latter to a
more useful name.

Don't do two allocations for the mod_Data structure.

The stream_decode() and file_decode() methods returned a boolean,
indicating whether they were able to decode the song.  This is
redundant, since we already know that: if decoder_initialized() has
been called (and dc.state==DECODE), the plugin succeeded.  Change both
methods to return void.

Instead of checking the stream_types bit set, we can simply check
whether the methods stream_decode() and file_decode() are implemented.

The variables mod_mikModInitiated and mod_mikModInitError were used to
control lazy initialization, but they are superfluous now.

The "mod" decoder plugin was being initialized lazily, but was
deinitialized unconditionally.  That led to segmentation faults.
Convert mod_initMikMod() to be the global module initialization
method.  The MPD core should care about lazy initialization.

Avoid while(true) loops, and convert them to a loop with a proper
condition.

Since the aac and mod plugins have told MPD that they cannot seek, MPD
will never send a SEEK command to them.  Removed the SEEK comand
checks from both plugins.

Don't pass the "seekable" flag with every decoder_data() invocation.
Since that flag won't change within the file, it is enough to pass it
to decoder_initialized() once per file.

The strings were constant, but the pointers weren't.  C syntax is
somewhat tricky..

All decoder_plugin structs are initialized at compile time, and must
never change.