fixed wording.
renamed unit tests and output images.
added unit test.
improved unit tests.
fixed major bug in Bezier curve intersection code.

the BezierCurveIntersector::intersect() method would report hits *farther* than the closest hit found so far (as indicated by the input value of the t parameter).
split interface and implementation.
fixed Travis build errors.
Merge branch 'master' into est_disney_material
Fixed PR comments.