multirotor_attitude_control performance improved, tested in flight. PID library new functionality and bugfixes.
Copyright fixes
sdlog2: FLOW message added, bug fixed in optical_flow topic
sdlog2: bugfix in FLOW message
Merge pull request #315 from DrTon/sdlog2

sdlog2: FLOW message added
Merge commit '8191130bbc8f2cbd53e69a7bcd1a4d4b1b2d68bb' into seatbelt_multirotor
Sonar added to position_estimator_inav
Merge branch 'att_control_der_fix' into seatbelt_multirotor
position_estimator_inav default parameters changed, some fixes