Add the distance calculation methods for the predictive timer

Creates the 3 different distance timer methods that will be
used to calculate the distance between two geopoints.
Each one's pros and cons are docuneted in the header file.

Also organizes the geopoint code a bit more.
Migrate the calls in predictive timer over to distPythag

Uses the new distance methods.  Also cleans up the compiler
warnings and removes the use of powf.