This reverts commit d7d9dbd2 by
reimplementing it with the current MPD API.

3 years ago, I was wrong about the "embcue" plugin being able to
replace this one, because "embcue" reads a tag named "CUESHEET", while
this plugin reads the "CUESHEET" FLAC metablock.  There's an important
difference between those two!

Avoids the recursion in LoadFile().

Avoid duplicate AllocatedPath::FromUTF8() invocations in two callers.

Allocate the frame pointers only when actually decoding the file.

This should not be necessary if libgme was built properly, and it may
break the build with libc++.

Wildcard matches are directly applied to all filenames in
subdirectories without any attempt at matching relative paths.

This change is based on the following feature request:

  http://bugs.musicpd.org/view.php?id=3729

bind fails with an "address already in use" error if the socket path
already exists.

This was broken by cbb595ba.

This was broken by 4f29034f.

The Mutex and Cond constructors are only "constexpr" with glibc, and
this is what this #ifdef is about.

Also uses the notification system to display tags.

Since we do not handle B_QUIT_REQUESTED because the BApplication
does not Run(), use the background flag to avoid showing up in Deskbar.

3D version reinterpreted from the official 2D design,
reusing existing Haiku icons.

Icon-O-Matic source file.
Same as data/artwork/icons/App_MusicPD in the Haiku tree as of hrev47609.

Haiku has struct ucred but no SO_PASSCRED (yet).

Haiku does not dump core, it just starts the debugger.

Only ignore indexes after first nonzero, preserving pregaps but
appending them to the previous track instead of prepending to the
current. The first index of the first track is used for the start time
regardless of its number. Unneeded bool last_updated removed.