Fix bug where we would load 0 length lists for various attributes, a bug
where we would load bogus rtpmap attributes for every payload type on
the m-line when no rtpmap attr existed, and fix a unit-test to squelch a
warning.
Implemented b= lines
Merge pull request #91 from martinthomson/sdpwrap

Adding offerToReceiveX
Merge pull request #93 from adamroach/sdp

Implemented b= lines
Merge pull request #92 from docfaraday/multistream_unit_tests

Fix bug where we would load 0 length lists for various attributes, a bug
Squelch some parse warnings in a test case.
Check that serialize->parse->serialize puts us back where we started
Merge pull request #94 from docfaraday/multistream_unit_tests

Squelch some parse warnings in a test case.
added support for DTLS/SCTP
more scpt verification
fixed bit madness for data channels
Add codecs in the answer
Merge pull request #95 from nils-ohlmeier/multistream

Basic SCTP support
Merge pull request #96 from ekr/MS_codecs_in_answer

Add codecs in the answer
Export the codec information in the track pairs
Merge pull request #97 from ekr/MS_better_track_pair_descriptions

Export the codec information in the track pairs
Improving test coverage for offerToReceiveX