Following the ed4d08189ea6e19a50e029e60da52d3583c39fbb
commit, this one fixes rtpasfpay to use packet length
as the payloaded data length, but also accepting it
as the full packet size for compatibility with
other implementations due to the lack of clarity of the
spec in this part.
Adds the brand new asfmux plugin, containing 3 elements:
asfmux, rtpasfpay and asfparse. This plugin was developed
as a GSoC 2009 project, with David Schleef as the mentor and
Thiago Santos as the student.