ORB topic advertisements are now global handles that can be used in any context. It is still possible to open a topic node as a publisher, but it's not the default. As a consequence, the type of the handle returned from orb_advertise has changed; all other API remains the same.
Now the mixer is a C++ library that can be fairly easily bolted into an output driver to provide mixing services.
Teach the FMU driver how to use it as an example. More testing is still required.
Solve the multiple publishers issue with 'control groups', one group per controller. Mixer inputs now specify both group and control offset within the group.
Avoid using %f when loading/saving mixers; use scaled integers instead.
