Merge remote-tracking branch 'MavLink/master' into mapCache

* MavLink/master:
  Remove dead parameter cache code
  Include type arg in method prototype
  New parameter cache loading spec
  Run DO_LAND_START as normal standaloneCoordinate
  Change MAV_CMD_DO_LAND_START to standaloneCoordinate
  Better error output
  Don't use home for last altitude
  Add gradient