pymavlink: cope with empty STRT message in APM:Copter dataflash logs
pymavlink: added support for PX4 native SD log format
pymavlink: added PX4 native gyro propogation code
pymavlink: raise version
pymavlink: cope with APM:Copter Mode log entry
pymavlink: added mode_string_acm()
pymavlink: cope with no GPSTime attrib on GPS messages
common: added SCALED_IMU2 message

for secondary sensors
common: added health bits for secondary sensors
pymavlink: fixed mavgraph for msg types ending in a digit