Function midLat( lat1, lat2 )

Description:
Determines the latitude midway between two given latitudes. This simply returns the mean of the two values, but is supplied for convenience to use alongside the midLon function.
Parameters:
lat1 (floating point)
first latitude in degrees
lat2 (floating point)
second latitude in degrees
Return Value (floating point):
latitude midway between the given values
Example:
midLat(23.5, 24.0) = 23.75
Signature:
double midLat(double, double)