APM_OBC: adjusted docs for FS_HB_PIN

thanks to Warren for the question
AP_Common: moved map_baudrate() into AP_Common

this version supports a much wider range of baudrates
GCS_MAVLink: moved main update() routine into GCS_Common.cpp

this fixes a common timeout error with loading large missions, and
means less per-vehicle code
Plane: changed baudrate parameters to 16 bit
Plane: update baud rate parameter descriptions
Plane: updates for new GCS_MAVLink API
Copter: change baudrates parameters to 16 bit
Copter: update baud rate parameter descriptions
Copter: updates for new GCS_MAVLink API
Rover: change baudrates to 16 bit

allows for much higher serial baud rates
Rover: update baud rate parameter descriptions
Rover: updates for new GCS_MAVLink API
AntennaTracker: updates for new GCS_MAVLink API
AutoTest: add -j option to sim_vehicle

new option controls the number of processors used during compile
GCS_MAVLink: Added message definitions for Rally Landing support.
GCS_MAVLink: Generated message code for Rally Landing support.
AP_Rally: More stateful.  Can now remember the last Rally Point chosen.
AP_TECS: added getter for flight stage.
AP_SpdHgtControl: Added FLIGHT_LAND_GO_AROUND FlightStage.
AP_Land:  A library supportingi landing from a Rally Point.