[nps] Started to add fixed wing support in NPS
[rotorcraft] improve in_flight detection heuristic

Simply checks if thrust, speed and acceleration are above a threshold.
Does not rely on RC thrust command anymore, but only on actual thrust command.
Not tested on real vehicle at all so far...

Attempt to improve issue #201 and replaces #468
[nps] A few more NPS for FW updates

 * tweaked FBW for USE_NPS, not SITL
 * Better support for AP or FBW or both
 * added start of a subsystem makefile
[fixedwing] energy_ctrl: don't keywords reserved in c++
[modules] light only for ap
[modules] only use sim_air_speed if not using NPS

for now...
[fixedwing] gps for nps sim
[fixedwing] cleanup autopilot makefile a bit
[fixedwing] ahrs and ins subsystems for nps target
[nps][fixedwing] updates for fixedwing support in NPS
[nps] minor cleanup
[nps] Detect nans and exit in JSBSim FDM
[nps] only declare isnan on osx
[conf][nps] Temporary addition of fw jsbsim models
Merge branch 'master' into nps_fixedwing

in order to get nps datalink fixes

* master: (92 commits)
  [rotorcraft] call ahrs_update_gps
  [boards] stm32f4_discovery board file for some testing
  [lpc21] only indentation cleanup
  [rotorcraft] PRINT_CONFIG_VAR for GUIDANCE_V_NOMINAL_HOVER_THROTTLE
  [conf] updates for fraser quad with spektrum
  [conf] stm32f4 discovery test board files
  [rotorcraft][stabilization_ref_quat] saturate rate and trim accel
  [rotorcraft] CAUTION! stabilization int_quat ref model scaling fixes
  [rotorcraft][stabilization] move some macros
  [rotorcraft] AHRS_FLOAT flag for float_cmpl_quat
  [rotorcraft] ins_int_extended without sonar
  [lisa] comments for the tunnel
  [conf] configurable spi for aspirin_2
  [boards] correct include guard for apogee 1.0
  [fix][lpc21] workaround for init of spi_slave_hs
  [modules] silence some warnings in imu_chimu
  [lpc21][uart] fix some unused arg warnings
  20s timeout and max 2 retries when trying to update_google_version
  [imu] aspirin_2_spi: default AHRS_PROPAGATE_FREQUENCY is 512
  [rotorcraft] only reset psi and integrators if previous mode was not attitude
  ...

resolved conflicts:
	sw/airborne/modules/sensors/airspeed_amsys.c
[nps][gps] calc utm, ned_vel, gspeed, course
[nps] datalink via ivy handling
[nps][conf] add needed sources/flags for imu/ahrs in fw nps
[nps] configurable jsbsim model and initial conditions from flight plan

If NPS_JSBSIM_MODEL is not defined, it defaults to the AIRCRAFT_NAME (previous behavior).
If NPS_JSBSIM_INIT is defined, that ic file is used, otherwise uses flight plan location.

NPS_INITIAL_CONDITITONS is not used anymore.
[conf][nps] replace INITIAL_CONDITITONS with JSBSIM_INIT in all airframes