- all content actions are now handled
- XEP-0167: the new contents of an offered SDP are added with a single content-add, the
contents sharing a single transport are bundled (XEP-0338)
- XEP-0167: the generated SDP declares the BUNDLE group of its own contents
- XEP-0176: one transport-info IQ per content. ICE data are keyed by content names.
- fix session-level ICE attributes and fingerprint
