[tests] add libpprzmath.so to LD_LIBRARY_PATH for running tests
[travis] run math tests
[omap] start basic spi driver

totally untested...
[modules] rotorcraft_cam: fix DEFAULT_MODE
[rotorcraft] navigation: fix NavCircleCount
[modules] dc: replace meter grid by proper distance autoshoot

Previously DC_AUTOSHOOT_DISTANCE would shoot on a 100m UTM north distance grid,
seems like nobody actually used that or found this useful.
So changing this to "proper" distance based autoshoot, storing the last shot position and
shoting the next one if dc_autoshoot_distance_interval is greater than distance to last saved shot position.
[modules] dc: remove unused dc_probing
[modules][messages] send pos as LLA in DC_SHOT and DC_INFO
[modules] dc: workaround to use waypoints in fixedwing and rotorcraft firmware
[modules] digital_cam_x: add dc.h header
[conf] example to test rotorcraft cam and dc stuff