AP_BattMonitor: fixed example build
AP_NavEKF: fixed return of offset in getVariances()
AP_GPS: cope with different MON-HW message size in u-Blox Neo7
RC_Channel: added static functions to simplify operations on all channels

this avoids vehicle code having to loop over all channels for common
operations
Plane: use new channel output API
Rover: use new channel output API
Copter: enable passthrough auxillary channels
Plane: fixed some warnings
AP_NavEKF : clean up convoluted logic used in sensor health checks

This doesn't change the behavior, but does make the code easier to
understand
AP_NavEKF : Relax aliasing check limits
This reduces the chance of noisy data inhibiting GPS glitch protection
AP_NavEKF : Limit rate of Z accel bias adaptation

Aliasing can causes the bias estimate to fluctuate very rapidly as it try's to to keep
to keep up which degrades the filters ability to switch between
accelerometers if they are alternately affected. T

This patch give a much more stable bias estimate during aliasing, and
allows the bias to adapt at a maximum rate of 1.0 m/s2 in 50 seconds
Copter : start dataflash logging on initialisation to aid EKF debugging
AP_NavEKF : Do not reset on GPS velocity timeout if good position data
AP_NavEKF : Improved GPS position glitch handling

When using GPS after previously rejecting it, the GPS position will
always be offset if outside the specified glitch radius. This was the
original intent of the design and makes handling of glitches smoother.

It has been tested on replay using glitchy flight data
AP_NavEKF : Fix dt scale error in Z accel bias rate limiter