cleanup of sensor readings and sensor driver API reorganization part 1
documented L3G4200D driver why 0x28 read was suddenly turning into 0xA8
removed old wiimotion averaging cruft from computeIMU
NOT FLIGHT TESTED

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@403 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61
oops, this should be a bitfield

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@404 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61