Fix a bug for circle arc intersections (sector is relative to origin)
Add tests for circle arc - line intersections
Refactor some private var access to getter calls for extensibility
Add some comments to collision geometry classes
Move the double comparison delta constant into test utils class
Add getter, contains and intersect to angle sector incl. test
Add some comments to sector and use getters instead of private fields
Add test for cirlce intersections when same circle
Fix bug for circle-circle intersect with same mid, add regression test

When two circles have the same centers there may be infinitely many
intersections (same radius) or zero (different radius). The latter case
was not considered.
Add circle arc - circle arc intersections with tests