Mission merge offboard + onboard and simplify

msg/mission.msg

src/examples/bottle_drop/bottle_drop.cpp

src/modules/commander/commander.cpp

src/modules/dataman/dataman.h

src/modules/logger/logger.cpp

src/modules/mavlink/mavlink_mission.cpp

src/modules/mavlink/mavlink_mission.h

src/modules/navigator/mission.cpp

src/modules/navigator/mission.h

src/modules/navigator/mission_feasibility_checker.cpp

src/modules/navigator/mission_feasibility_checker.h

src/modules/navigator/mission_params.c

src/modules/navigator/navigator.h

src/modules/navigator/navigator_main.cpp