Add FrSky telemetry application.
This daemon emulates an FrSky sensor hub by periodically sending data packets to an attached FrSky receiver.
Added support for a total of four control groups to the IO driver and IO firmware. This allows to run auxiliary payload. Cleaned up defines for RC input channel counts, this needs another sweep to then finally allow up to 16 mapped channels and up to 20-24 RAW RC channels
fix small copy paste error in px4io driver
px4iofirmware: in manual mode: ignore control indices which are not controlled by the rmeote control
px4io frimware: improve handling of manual mode when fmu is still healthy, use data from fmu for channels which are not controlled by rc
px4iofirmware: improve check for rc controlled channels in manual mode
PPM channel count detection is now using a more paranoid approach.
Added performance counter for write IOCTL
Added average as direct output
Allowed custom battery scaling on IO
Fixed bracketing error
Merge pull request #557 from PX4/custom_io_scale

Custom io scale
Counting channel count changes
Merge branch 'custom_io_scale'
Add tight RC test
Added missing folder
Merged master
Fixed compile error
Fix usage of wrong constant for RC input channels
Support 18 channels correctly on FMU