Renamed all solitary occurrences of 'angle' to 'pangle'

The word angle is currently denoting either a phi-value or a theta-value from the parametric axis azimuth or polar (in combine these axis are currently known as 'AngleSpace').
However, neither phi- nor theta-values denote angles in the euclidian space. Only when the Surface mapping from the 'AngleSpace' is a perfect sphere do phi and theta truthfully reflect the angles in euclidian space.
phi and theta will always map to some angle, but the angular momentum is non-constant, making them useless for any practical usages as angles.
I'd we change the current usage if the word 'angle' into the word 'pangle' (an 'angle' from Parametric space) we can reserve the word 'angle' to denote proper useful angles in the euclidian space.

This fixes #95