additional upper pitch limit during launch

The pitch limit can be used by the laucnhdetector to limit pitch during
critical phases of a launch. For example this can be used to limit pitch
while attached to a bungee differently from the standard pitch limit.
Merge remote-tracking branch 'upstream/master' into launchpitchlimit_master
launch pitch limit: add mtecs interface
Merge branch 'launchpitchlimit' into launchpitchlimit_master
Merge pull request #1356 from PX4/launchpitchlimit_master

FW: additional upper pitch limit during launch