Merge branch 'origin/dev'
isSimple fixed for triangles.

If polygon vertex count is 3 the method incorrectly returned false and detected the polygon as selfintersecting.
Merge pull request #4 from pshtif/patch-1

isSimple fixed for triangles.
- Fixed isCCW to assume y-axis pointing down (thanks to @pshtif, closes #6)
- Added makeCW to PolyTools
- Reworked algorithms to cope with the fix
- Fixed edge-case for isConvex
Simplified SubDecomp constructor logic
License header in files