Initial UAVCAN integration. The library compiles successfully, CAN driver appears to be working properly. There is one hardcoded path in the module makefile that needs to be fixed; plus the compilation will likely fail unless arch/math.h contains log2l()

mc_att_control: yaw feed-forward in manual control modes fixed

Proper data manager restart handling

rcS: add options to disable or fake gps output

this allows the safety switch on px4io to be forced off

this allows the FMU to force the safety off on the IO board. Useful in
two cases:

 1) vehicles where the safety switch is impractical or not useful
 (eg. HAB planes or internal combustion motors)

 2) doing ESC calibration on multi-copters

also fixed preceding mask calculation in show heaps

Introduce SYS_RESTART_TYPE parameter having one of 3 values: boot
restart, inflight restart, or unknown restart, and defaulting to unknown
restart.

px4io.cpp sets this parameter according to the type of restart detected.

dataman.c retrieves this parameter and clears data entries according to
their persistence level. Does nothing if unknown restart.

mpc_local_pos + rc_timeout

Renamed parameters which changed from RAD to DEGREES to avoid user confusion. Also made naming of the two parameters more consistent.

Arm/Disarm duplication removal and support for Disarm in VEHICLE_CMD_COMPONENT_ARM_DISARM

Mag declination hotfix

Compile pedantic

warnings: don't spam with warning for missing field initializer

sensors: Keep looping in sensors app even if gyros do not update any mor...

launchdetector: fix copyright header

Sensor error handling

Indoor gps simulation mode

add tags file to .gitignore