[fix][actuators] fix asctec error handling

The previous fix causes the asctec controller V1 to crash on LPC.
This fix the problem for V1.
The same error handling is integrated to V2 but not tested, although if
should be much better than the previous one (and the one before...).
[umarim] release config file for Umarim Lite v2
[nps] fix typo: really set mag instead of gyro available in feed_mag
[nps] use magnetic field from airframe file if defined there
make it possible to disable the bypassing of the ahrs via define
[examples] set correct AHRS_PROPAGATE_FREQUENCY for some examples with aspirin 2.1
[rotorcraft][ins] set hff frequency according to AHRS_PROPAGATE_FREQUENCY
[units] fix display of deg in messages (no conversion)
[units] yet another units fix

Units that can be automatically converted should come last so other
possibilities are tested first. (ok, that is a lazy and fragile
solution...)
A the type of auto conversion ("display" or "code" can be changed only
for conversions that were already using auto mode (eg. deg <-> decideg
will not be auto converted)
[build system] prefer compiler/toolchain found in path
fixes #231
also use a common makefile for finding the toolchain
see #244
release version v4.0_stable
Classix Still Working fine in v4.0
Update fbw <-> ap splitting
whitespace fix merge conflicts
[fix][modules] photogrammetry_sweep_angle in radians
[fix][modules] fix switching power on for digital_cam
[modules] digital_cam: Solve static inline compiler problem on STM32
Merge pull request #254 from tudelft/v4.0_classix

Bugfix: original separation of fbw <-> ap was violated. Fixed so Classix is still completely supported.
Merge 2 consecutive logfiles back into 1 file (e.g. server was restarted during flight)
[tools] gen_settings: error if a handler but no module attribute is specified
previously it just silently ignored the handler, which is really really bad!
[fix][settings] specify correct module for some settings handlers