smaccmpilot: rename Servos type to Motors

* servos is the name in mavlink, but otherwise there is no reason
  to follow it.
smaccmpilot: refactor motors task into a motors mixer task

* implemented empty mixer, need to go back and do that properly
flight support: fix build, fix benign warnings
px4ioar-hw-test: stubbed out haskell definition, test app, and c build