TradHeli - change throttle range back to 0~1000 (was temporarily changed to be 1250~850 which limited the range of the swash plate's vertical movements)

we were not dropping altitude in the change_alt test

increased timeout, added check for home location, and fixed failure
testing on timeout

ensure heli builds are tested

TradHeli - fixed small parameter bug affecting helis.  The servo parameters were declared as GSCALAR instead of GGROUP in Parameters.pde.
also renamed heli parameters from _coll_ to the more descriptive _collective_

          also removed reference to DCM (no longer required) and removed some old code.

This interferes with the calculation of the centripetal acceleration
calculation in the DCM code. We need a new way of handling pitch trim

this increases the noise to 2 bits, which actually can have the effect
of improving accuracy, as it leads to better averaging

if we don't have a GPS or the GPS doesn't have a good lock then we
can't rely on the ground speed for adjusting the acceleration vector