Add back some (currently unused) files lost in an earlier NuttX merge
HOTFIX: Fixed HoTT compile error, fixed MAVLink crash
Fixed test outputs, decoupled tests from NuttX low-level output via message() macro
Merge branch 'master' of github.com:PX4/Firmware into sunday-i2c
Merge branch 'tests' of github.com:PX4/Firmware into sunday-i2c