Proposed fix for collision detection

Added cast to float in extent_x and extent_y initializations.
The straddles() method now checks all four points for intersections.
Removed use of projection() within projectOntoAxis() as it appears to be unnecessary?
Fixed integer division truncation issue.
Merge branch 'patch-2' of https://github.com/sjp55/StarshipFontana into sjp55-patch-2

Conflicts:
	src/SFBoundingBox.cpp
Merge branch 'sjp55-patch-2'