Plane: altitude for do_set_home() is in meters
RC_Channel: constrain norm_input() to -1 to 1

if RC is not properly calibrated we could get a value beyond 1, which
could cause some flight modes to exceed the roll/pitch limits of the
aircraft
Plane: use set_mode() in do_RTL()

thanks to Randy for spotting this
AP_GPS: fixed example builds with change to init()
Git: ignore test.ArduPlane, test.APMrover2

Remove redundant dataflash.bin and eeprom.bin which are already covered
by *.bin exclusion