pymavlink: extract separate missions in mavextract
pymavlink: raise version for release
pymavlink: added gains to demix functions
pymavlink: fixed X range calculation for multiple data files

this prevents the X range getting a too many ticks exception when we
are plotting multiple files with different time ranges.

Also adds --multi option to make multiple file plots not change colour
per file
pymavlink: Allow headless operation in mavgraph by providing an output file name.
ardupilotmega: merged in motor test command from ardupilot
common.xml: added MAV_CMD_DO_INVERTED_FLIGHT

used to control inverted flight in a mission
Force people to use the right header with an #error.