Adoptation to FFmpeg 2.2+

Complex rework to make library work with latest FFmpeg. Basic work to
support new AVBuffer functionality (not realy useful now, only basics
that used in AVPacket/AVFrame).

Other changes:
* Container::writePacket() now use interliave writing by default
* Packet now movable type (c++11)
Added stream coder context coping

Also various cosmetic changes