.. rather then append to the end of the previous one

Cuebreakpoints from the cuetools package has three modes of operation,
and the default is to append pregap (INDEX 00) to the end of the
previous track. This is the behavior most compliant to the existing
cue files.

Here is the patch which fixes the issue. I borrowed bits of
implementation from cuebreakpoints. I assumed that the whole audio
file must be covered by head-to-head going tracks, which is how
hardware CD players probably work. In cue_tag I changed rounding from
rounding up to rounding down because the thing in mpd which calculates
actual track duration (and current position) rounds it down, and I
didn't want to see in my playlist values different from whose in a
now-playing progress bar.

I've compared the resultant mpd behaviour with "mplayer -ss MM:SS.MS"
where the time was supplied by cuebreakpoints and noticed that mplayer
started each track a bit earlier then mpd, though this was the same
before the patch.

This playlist plugin handles FLAC files with embedded CUE sheets.

Major API redesign: don't let the caller allocate the input_stream
object.  Let each input plugin allocate its own (derived/extended)
input_stream pointer.  The "data" attribute can now be removed, and
all input plugins simply cast the input_stream pointer to their own
structure (with an "struct input_stream base" as the first attribute).

This patch adds practical usefulness to the CUE playlist plugin.

The caller should be responsible for building the absolute URI.

This plugin is the groundwork for MPD's future generic CUE sheet
support.  That's not complete yet, e.g. there is no way for a playlist
plugin to address an arbitrary position within a music file.

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.

This new plugin parses extm3u files.  Files without the "#EXTM3U"
header are still parsed by the plain old "m3u" plugin.

The caller is responsible for verifying the song URI.

Based on the XSPF playlist plugin.

Added a missing "break".

This plugin will replace the last.fm input plugin, once the playlist
API is integrated into MPD.

Based on this API, we will add parsers for EXTM3U, PLS, ASX, last.fm
radio and others.

There is no integration into the MPD core yet.  Right now, we have a
command line test program.  This is work in progress.