Autoconf/automake support for libcue which
is needed for cue/cue_tag.h/.c.
Libcue will have/has pkg-config support
so this is fairly straightforward.

With these methods a tag struct can be created
from the cdtext information in a cue sheet.
The methods depend on a cue parsing library.
Reading from strings (char*) as well as from
a file (FILE*) is supported.

This is a little ugly, but as nextSongInPlaylist is both called when
queued is update (in case playlist ended) and for user "next" command,
there isn't any other (simple) solution

Consume mode removes each song played

In the MPD_AUTO_DISABLED() function, I forgot to check for "explicitly
disabled".

Ths usual defaults updates, this includes clarifications, cleanups, updates
and fixes.

MPD_AUTO_PKG() runs pkg-config and then forwards control to
MPD_AUTO_RESULT().  This is a commonly used short cut.

Don't add those to MPD_CFLAGS and MPD_LIBS.

Don't add those to MPD_CFLAGS and MPD_LIBS.

Don't add those to MPD_CFLAGS and MPD_LIBS.

This patch adds a small autoconf M4 library which deals with
auto-detected features.  The default for those features is "auto",
which is like the old default: if the library is present on the
system, enable the feature, disable otherwise.  If the user explicitly
enables that feature (--enable-alsa), and the library is not present,
configure must fail, because it cannot fulfill the request.

Previous cast to float didn't have any effect because one value is uint
and the other is a floating type but the number itself is even..
This caused some tracks to end before they were really at an end.

Added an assertion in mixer_set_volume().  Removed the range checks
from the ALSA and OSS plugins.

The "mpcdec" plugin is based on the libmpcdec library.

Renamed variables and functions.

The strings passed to tag_pool_get_item() are not null-terminated, and
the caller passes the string length.  Don't assume it is
null-terminated anyway by using strcmp().

We're using GLib macros which were introduced in GLib 2.6, like
G_GNUC_MALLOC.  Let's just drop support for GLib versions older than
2.6 instead of adding more complicated compatibility hacks.

socket, because there is no ioctl for non-sockets on Windows

networking, select(), ntohl(), etc.

Simplify initialization and finalization.

There are numerous race conditions between the libpulse thread
(pulse_mixer.c callbacks) and the rest of MPD.  Protect the volatile
attributes of the pulse_mixer struct with a mutex to fix that.

Eliminate one indent level.  Also remove several debug useless debug
messages.