Plane: fixed target speed reload on landing

thanks to Doug for this fix!
autotest: allow sim_arducopter.sh to take mavproxy parameters
Plane: make CIRCLE mode hold altitude

this will prevent us losing a lot of altitude during the initial
failsafe phase
build: fixed etags target
Plane: update firmware version to 2.69
Tools: added build_all_px4.sh

this brings px4 into autotest
Plane: fixed an integer multiply error that caused poor altitude on landing 

the control of altitude between waypoints was broken due to an integer
overflow
AP_InertialSensor: expand register range in MPU6000 _dump_registers()
Plane: enable MAV_CMD_DO_DIGICAM_CONTROL
SITL: added SIM_GPS_TYPE control

for choosing what sort of GPS to simulate
SITL: added simulation of the original MTK GPS
SITL: added support for MTK16 and MTK19 simulated GPS types
SITL: improve time field handling in simulated GPS
SITL: added SIM_GPS_BYTELOSS option

this allows testing of protocol recovery after losing bytes on the GPS
serial link
AP_GPS: removed the old MTK16 driver

the MTK19 driver supports both the 1.6 and 1.9 protocol
AP_Mission: Command and waypoint handling library.

- Reads and writes MAVLINK commands to/from storage.
- Contains a waypoint queue of previous, current, and after waypoints.
- Provides commands associated with current mission leg.
- Allows incrementing waypoints and changing to specific waypoints at anytime.
- Handles DO_JUMP commands while maintaining a valid waypoint queue.
- Performs error checking on waypoint values.
AP_Mission: Removed cliSerial and uncrustified files
AP_Mission: Addition of command_index() function, that just returns the current index (_index[1])
AP_Mission: Added check for number of jumps remaining in get_new_cmd()
ArduPlane,AP_Mission: Modified get_cmd_with_index and set_cmd_with_index functions to use AP_Mission.