Commits work on progress. Prepares to keep video frame memory entirely in the native, non-Java heap.

Refactors AVFrame, ByteBuffer and ByteBufferPool. Prepare to invoke FFmpeg's avcodec_free_frame(AVFrame **) which is the new way to free AVFrames.

Adds support to encode and decode VP8. Note that a vp8 encoder and decoder need to be build into the jnffmpeg library in order for this to work, and prebuild binaries aren't ready yet.

- Removes the DirectSound support from PortAudio in order to prevent issues with bad audio quality.
- Attempts to recognize USB PortAudio devices on Windows as such, ignores the virtual Microsoft Sound Mapper devices to avoid user confusion. Contributed by Vincent Lucas.

Commits an initial version of the libjitsi library which should be fully functional with respect to neomedia/MediaService and should be usable with and without OSGi.