Diagonal Fences

[knpa]

To be able to draw fences in the main window which aren't orthogonal rectangles, i.e. are slanted to the left or right.

[chrfi]

because this new feature requires collision detection to be used now in two places in the code (in quadtreenode for subsetting and in the loaders for this fencing) i have moved the collision detection algorithms out into there own file and rewritten large chunks to make future feature additions easy. There are now algorithms which can be combined to handle any convex shape collision.

the interface remains the same (apart from the addition of the new load method ofc), however under the hood requests for subsets and anything else that tests collison pass arrays of points rather than a set amount to allow them to be used for a range of shapes.

[harg]

DONE. There is now a choice between slanted and non-slanted boxes for both fences and profiles.