Turned config.py into actual python file
SVG reader now ignores everything in white and orange.
(colors defined in config.py 'ignored_colors')
Config available to both backend (config.py) and frontend (app_settings).
Introduced material type drop down (driven via config.py)
Material types implemented.

Material types are defined in config.py, get passed to the front end, which
turns it into correctly configured passes.
Order for material defined cuts, and on-the-fly material type selection.