AP_Declination: The exception signs unpacking logic was incorrect. I was shifting a 1 value left y%8 which would have needed a the signs to be packed right to left. My packed signs byte was packed left to right (left most being the 0 position) so I needed to reverse the shifting.

AP_Declination: In order for the bitwise & operation to work, negative signs need to be represented by 1s instead of 0s. Changed so that negative signs are represented by a 1 in the packed signs array. Updated lookup logic to reflect this change.

AP_Declination: Added original array to test sketch. Added loop to validate new compressed array against original in 1 degree steps.

AP_Declination: Moved rows with large spikes in delta to their own unsigned exception rows. The signs are in a separate packed array.

AP_Declination: Implemented Delta Encoding and Run-Length Encoding. Added method to traverse the compressed array and return the lookup value based on the same lat_index/lon_index that was used before.

AP_Declination: Reduced the size of the lookup table to support -75 <-> 70 latitude range. This allows the datatype to remain int8_t.

fix possible issue loading stream rates
fix tracker ranges
add more ch6 options
modify mag calib with throttle

when MANUAL_LEVEL is set to 1, we don't do accelerometer levelling at
startup, and instead used the values saved in the EEPROM. This makes
it easier to do levelling on the bench, or once for a series of
flights for the day

when a user first connects with USB, and later switches to the
telemetry port without restarting we were getting zero for error_yaw
in the logs, as AHRS.get_error_yaw() was being called twice.

This ensures we give the last value after the counter is reset

explain the algorithm a bit more

        #define CH6_YAW_KI 24
        #define CH6_ACRO_KP 25
        #define CH6_YAW_RATE_KD 26
        #define CH6_LOITER_KI 27
        #define CH6_LOITER_RATE_KI 28

AP_OpticalFlow - small bug fix to ensure init attempts to read the product id 3 times before giving up

add read delay on write for serial
add tlog to gpx creation
fix issue 583 - georef image with a tlog

this caused problems with random()

This adds a large amount of noise robustness to the compass offset
learning algorithm, at a cost of 120 bytes of memory. The changes are
based on a long discussion with Bill Premerlani.

we don't need to add count any more, as floating point maths doesn't
need to round up

this seems to work much better than the old algorithm, converging
faster and more accurately. Even better, it has no linkage to DCM, so
no possibility of nasty feedback effects

fix antenna tracker issue with saved settings
add pretyping to config list
add rawlogs
modify mavlink log graph interface. 2 x yaxis & roll,pitch,yaw now in degs
update dataflash log format - thanks randy
update google earth interface refresh to 0.3 sec

APM_RC - moved Force_Out0_Out1, Force_Out2_Out3 and Force_Out6_Out6 to APM_RC parent class because it's already implemented in the APM1 and APM2 child classes anyway

Filter - added simple LowPassFilter (simple but it's possible to make errors with simple stuff too so might as well have one)