Added submodule ffmpeg, selected release version 1.2
avcodec_decode_video2 may not consume the whole AvPacket in one call.
Replaced deprecated avcodec_decode_audio3 with avcodec_decode_audio4

AudioDecoder and VideoDecoder implementation is more similar now.
Audio samples are memcopied from FFmpeg buffers into buffers provided by
AudioOutput.
Porting to FFmpeg 1.2 (part 1)

- Uses a patched FFmpeg version with ffurl_register_protocol available
  in API.
- Added build subdirectory to build FFmpeg and sinema. At runtime the
  private FFmpeg version is found via RUNPATH. This allows to install
  FFmpeg in parallel to a version provided by the Linux distribution.
- SampleFormat -> AVSampleFormat
Porting to FFmpeg 1.2 (part 2) audio decoder emits planar formats
Optimized interleave function in AudioDecoder
Fixed interleaving of planar audio formats
Using av_frame_get_best_effort_timestamp to determine PTS
Displaying available video, audio and subtitle streams in menu
Removed m4 files provided by package autoconf-archive
Ported to Linux Mint 16

FFmpeg in git submodule is installed into /usr/local.
Fixed calculation of PTS in AudioFrame objects

Replaced integer division with floating point division.
When one FFmpeg audio frame was split into 2 AudioFrame objects then the
same PTS was set in both. As a result VideoOutput received corrupt
AV sync info and video frames are not shown in a regular interval.
FFmpeg patch is available in forked github repository