UAVO browser was emitting updates on every UAVO receive event. This was
inefficient and led to a high processor usage, as well as causing the
browser to drop a high percantage of updates.

The patch centralizes the dataChanged emits, and places them on a timer.
UAVO browser processor load fell over 50% and data updates beyond 3Hz are
now reliably shown.
Updated updateChanged() throttling to act directly on view, instead of data.
Moved all awareness of update ranges out of data model and into tree view.
Added dynamic throttling to UAVO browser. The throttling updates the UAVO
browser at the speed of the fastest visible UAVO, up to a certain
threshold. After this threshold, the throttle is scaled exponentially,
such that the maximum refresh rate is around 30Hz.
Fixed gravity settings dialog.
Update makefile to include help documentation for wipe, and to sanity check
environmental variables.
Added "package" to Makefile help.
Fixed parameter strings in Makefile sanity check.
FixedWingFollower: Allow circling in PH/RTH

Previously only a position to fly to was allow in the
fixed wing follower which resulted in repeatedly passing
over that coordinate and turning around.
Paths: Make ModeParameter the radius for circle position

Previously the radius was calculated from the start mine end
position but there is no reason to use that representation
other than to be confusing.
RTH/PH: Mode is now airframe type dependent

Fixed wing aircrafts should hold position by circling
a location.  Hardcoding to circle left with 50 m radius.

VTOL behavior unchanged and tries to hold exact location.
FixedWingFollower: Use math library bound
FixedWingFollower: Only update objects that changed

Previously every object was updated every cycle.  This reduces
the amount of locking of the semaphore.
FixedWingFollower: Remove some unused object accesses
Simulation: Add airspeed to fixed wing simulation
FixedWing: Some style clean up
Renamed ModuleSettings->State UAVO.
Updated admin state name change.
FixedWingFollower: Make RTH/PH radius settable
FW Sim: Add comment about assumptions