Allow reusing Tag instances.

The "bool" type is built-in.

Implement the "scan_stream" method that can read tags from any
input_stream object.  This requires a FLAC__IOCallbacks implementation
based on the input_stream API.

Merge common code.

Not using libFLAC++ because this library adds a lot of overhead due to
virtual method calls.  This new class library is zero-overhead.

This has been deprecated by the "embcue" playlist plugin.

Pass a callback table to scan_file() and scan_stream(), instead of
returning a tag object.

Don't calculate the song duration when the sample rate is 0 (division
by zero crash).

Adds mixrampdb and mixrampdelay commands.  Reads MIXRAP_START and
MIXRAMP_END tags from FLAC files and overlaps instead of crossfading.

Don't allocate each replay_gain_info object on the heap.  Those
objects who held a pointer now store a full replay_gain_info object.
This reduces the number of allocations and heap fragmentation.

Make this code is reusable.

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.

If a feature is disabled, don't compile the source file at all,
disable it completely in Makefile.am instead.

Yet another patch which converts pointer arguments to "const".

The ID3 code uses only the public tag API, but is otherwise
unrelated.  Move it to a separate source file.

Try to only include headers which are really needed.  We should
particularly check all "headers including other headers".  The
long-term goal is to have a manageable, small API for plugins
(decoders, output) without so many mpd internals cluttering the
namespace.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7319 09075e82-0dd4-0310-85a5-a0d7c8717e4f

[ew: cleaned up the dirty union hack a bit]
Signed-off-by: Eric Wong <normalperson@yhbt.net>

git-svn-id: https://svn.musicpd.org/mpd/trunk@7180 09075e82-0dd4-0310-85a5-a0d7c8717e4f