When libid3tag is disabled, the libmad decoder plugin is unable to
identify ID3 frames.  If the file starts with an (unidentified) ID3
frame, it assumes that the file is not a valid MP3 song.  This patch
solves this by adding minimal stubs for the ID3 functions.

The function tag_ape_load() retrieves a 32 bit unsigned integer from
the input file, and passes it to g_malloc().  This is dangerous, and
may be used for a denial of service attack on MPD.

Extend the tagLen check after reading it.  Removed the second
(redundant) check after the subtraction.

The expression "tagLen - size > 0" may result in an integer underflow
and a buffer overflow, when "size" is larger than "tagLen".  "size" is
read from the input file, and must not be trusted.  This patch changes
the expression to "tagLen > size", which is a lot safer.

--enable means "enable", not "disable".

If the encoder plugin API is disabled at compile time, don't compile
test/run_encoder.c.

The first patch by Patrick didn't work, because his "#ifdef HAVE_OSX"
line would have required config.h.

Initialize flac_data.tag right after flac_data_init().  This way, the
"goto fail" won't jump to the point where tag_free(NULL) can be
called.

On Mac OS X, the httpd plugin cannot be compiled, because OS X's
system headers do nto include sys/types.h, although they use
u_int32_t.

Don't free an internal configuration value in log_init().  Call
config_get_path() instead of manually calling parsePath().

When the filesystem_charset is changed in mpd.conf, MPD should discard
the old database.  In this error branch, MPD did not fill the GError
object properly, and logged a warning message instead, which caused a
segmentation fault.

- introduce a section explaining the mpd.conf format, as done in the man page:
is it better to re-explain it here or ointing the user to the man page,
avoiding information dupplication?
- reorganizze some sections of the manual to give them a linear aspect...

When the PAUSE loop ends, re-check the next command before calling
ao_play() again.

When MPD was paused, and the client sent the "stop" command (or
"clear"), a glitch caused MPD to continue playback for a split second.
This was because audio_output_all_cancel() calls
audio_output_all_update(), which reopens all output devices, and
re-ignites the playback loop.

When decoding a local file, the decoder thread tries to run all
matching decoders, until one succeeds.  Both file_decode() and
stream_decode() can decode a stream, but MPD closes the stream before
calling file_decode().  Problem is: when this decoder fails, and the
next's stream_decode() method is invoked, the input_stream is still
closed.  This patch reopens it.

Several users had problems with binding MPD to "localhost".  The cause
was duplicate /etc/hosts entries: the resolver library returns
127.0.0.1 twice, and of course, MPD attempts to bind to "both" of
them.  This patch makes failures non-fatal, given that at least one
address was bound successfully.  This is a workaround; users should
rather fix their /etc/hosts file.

Dump each socket address before binding to it.

list_OK is returned only after command_list_ok_begin.

This warning is useless.  I assume the author added it for debugging
purposes.

When client_defer_output() aborts the connection to the client,
client_write_output() called client_write_deferred() anyway.  This
caused an assertion failure.  Fix it by checking for the "expired"
flag again after client_defer_output() returns.

I'm hunting down a bug where client->channel==NULL during I/O
operations.  These new assertions help avoid this kind of bug in the
future.

Renamed all remaining CamelCase functions.