Add Excellon support
Merge pull request #3 from hamiltonkibbe/excellon_support

Add Excellon support
Add setuptools support
start arc
Add mode statement parsing
Doc update
doc update
doc update
doc update
Add tests
Add layer names file
Working region fills and level polarity. Renders Altium-generated gerbers like a champ!
Added excellon format detection
Doc update
Readme update
update docs and example images
Merge branch 'master' of https://github.com/hamiltonkibbe/gerber-tools
Add SVG transparency
Add primitive definitions and bounding box calcs for DRC
Fix parsing of Unknown statements