BumpToNormalMap

Merge pull request #2 from Poikilos/naming-conventions

Return the path from the function. Add a docstring.

Only consider "bump" in the old name based on a "whole word only" search.

Use the old name (but remove "bump" from it if present) in the new name (with "normal"). Fix invalid escape sequences.

Change comments to a stanard Python docstring (sets __doc__). Make sure output_format is correct, otherwise raise ValueError.