Introduced a decay mode and a TC toggle mode command that can be
mapped to any switch from the airframe file instead of hardsetting in the
code.
Setup decay and tc toggle switches and threshold values in airframe file.
Set TC toggle to mode switch; motor kill to GEAR. AUX4 now free for auto
mode toggling
Allowed mapping of gain set changes to any radio switch via the airframe 
file.
Added radio autonomous mode selection switch to enable as many as 9
modes.
Added additional modes to samara airframe file
[SAMARA] Setup additional autonomy level modes for each major mode.
Currently enabled ONLY for mode manual (HOVER/VTOL OPS)
[SAMARA] Setup additional mode change parameter in autopilot mode 
selector function AP_MODE_OF_PPRZ