Merge branch 'master' into navigator_rewrite

Conflicts:
	src/modules/commander/commander.cpp
	src/modules/commander/state_machine_helper.h
	src/modules/mavlink/mavlink_messages.cpp
Merge branch 'navigator_rewrite' into navigator_rewrite_estimator
Merge branch 'navigator_rewrite' into navigator_rewrite_offboard2_merge
Merge remote-tracking branch 'px4/mavlinkexternalsetpoints' into navigator_rewrite_offboard2_merge
estimator lib: Improve error reporting
estimator: Use improved error reporting API
Merge branch 'navigator_rewrite_estimator' of github.com:PX4/Firmware into navigator_rewrite_estimator
estimator: Use the right perf counters to measure the quantities we are interested in
mtecs/wind: store wind variance
navigator: NavigatorMode and MissionBlock API cleanup
Merge branch 'navigator_rewrite' into navigator_rewrite_drton
Support for List, Open, Read, Terminate commands

Fixed various bugs. Flattened Mavlink::Session class while fixing bugs
in this area.
Merge pull request #1083 from DonLakeFlyer/mavlink-ftp

FTP List, Open, Read, Terminate commands working end to end with QGC
estimator: Fix minor reporting issues
Remove old TECS implementation - we can really only decently flight-test and support one.
geo lookup lib: Moved to separate module and compiling with -Os to save some precious flash
Comment fix in perf counter header, no code changes.
Enable new lookup lib
Merge pull request #1085 from PX4/geo_flashefficiency

geo lookup lib: Moved to separate module and compiling with -Os to save ...
Merge pull request #1084 from PX4/mtecs_pure

Remove old TECS implementation - we can really only decently flight-test...