For type safety and code readability.

Move to fixed-point integers instead of floating point.

Move and refactor code from the Wavpack decoder plugin.

Move code from the "mad" plugin.

Move code from the "mad" plugin.

Use only ConfigData.hxx in plugin sources to reduce header
dependencies.

Avoid duplicating the tag.

Let the function decoder_replay_gain() update
decoder_control::replay_gain_db instead of letting each decoder plugin
take care for that.

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

Use input_stream.uri.

This function replaces the replay_gain_info parameter for
decoder_data().  This allows the decoder to announce replay gain
changes, instead of having to pass the same object over and over.

Remove the data_time parameter from decoder_data().  This patch
eliminates the timestamp counting in most decoder plugins, because the
MPD core will do it automatically by default.

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.