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 remote-tracking branch 'upstream/master' into new_state_machine

Conflicts:
	src/modules/sdlog2/sdlog2.c
	src/modules/sdlog2/sdlog2_messages.h