Closes https://github.com/MusicPlayerDaemon/MPD/issues/1294

This commit also increases the PROTOCOL_VERSION so clients can detect
the availability of the feature.

During the libfmt migration, I converted "%1.3f" to just "{:1.3}"
without the "f" suffix, but libfmt defaults to scientific notation,
which can break some MPD clients.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1291

Requires PipeWire 0.3.32.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1283

This bug caused a 9 second offset in all time stamps.  Due to that,
the Snapcast server thought the chunks are too old and discarded them.

Fixes https://github.com/MusicPlayerDaemon/MPD/discussions/1287

This replaces the output parameter (which is bad API design).  As a
side effect, it fixes the bad [[gnu::pure]] attribute added by commit
a636d212 which caused optimizing compilers to miscompile calls to
that function.  "Pure" functions can be assumed to have no output
arguments, so the compiler can assume the function doesn't modify
them.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1282

Fixes a build problem on platforms where stdio.h is not included
transitively. snprintf() is defined in stdio.h.

Fixes https://github.com/MusicPlayerDaemon/MPD/discussions/1281

The problem occurred when there was libfmt-dev installed, but it was
too old (e.g. on Debian Buster), and Meson used the wrap fallback.
Those internal MPD libraries where the libfmt dependency was not
declared were still using the old system libfmt headers, which are not
ABI-compatible with MPD's own libfmt build.

Should have been part of commit
ef24cfa5

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1279

Fixes part 2 of https://github.com/MusicPlayerDaemon/MPD/issues/1279

Fixes part 1 of https://github.com/MusicPlayerDaemon/MPD/issues/1279

Whoops, I misplaced this one.

Another one from https://github.com/MusicPlayerDaemon/MPD/issues/888

Closes https://github.com/MusicPlayerDaemon/MPD/issues/888

Forgot that in commit 9a766f4c

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1115

Some users want certain clients to fully control playback, but do not
want them to be able to trigger database update.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1124

From the feature request: "I generally like to have crossfade on, but
when it happens during such short tracks (e.g. 20 seconds or less) it
doesn't really sound good as those tracks are not really meant to be
crossfaded and intended to act as a bridge on their own."

Sounds reasonable.  This commit doesn't add an option, but hard-codes
the limit to 20 seconds.  If it turns out that users want to have it
configurable, we can still add the option.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1184

This reduces duplicates in the music database by hiding the original
song file when it is referenced by a CUE sheet.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1275

Don't allocate any memory until the output is really enabled.

The implementation was removed 12 years ago in commit f6455d5f and
nobody missed it.

This reverts commit 9200fa6d.  It was
wrong because it works only if the target song has already been
scanned.