Added documentation.
Added LED_STRIP feature, can only be enabled under certain circumstances
depending on target due to pin/timer mappings - see documentation.
Previously, on the OLIMEXINO at least, initial readings are lower than
normal readings and that meant that the battery warning voltage was
incorrectly set.
using different values in different.
The cause was the IMU init code which triggered calculation was never
called after switching profiles - it couldn't be called twice because it
also initialised the compass.
The solution was to decouple compass initialisation from IMU
initialisation and extract the code to recalculate throttle angle scale
to a new method.
It was noticed that GPS startup time increased when the change was made
from using EGNOS by default to using AUTO by default.
The default is still AUTO but faster GPS startup times may be achieved
by telling the GPS receiver what region you are in.
This also removes more unfinished MTK gps provider support.
