Bugfixes in build algorithm and 2D-Drawmethod for testing purpose

~Re-Edited HappahTypes
~FastKdTree: unordered_map of classification labels now correctly updated
 using pair.second = <value>
~Replaced trianglesLeft with triangles in doBuildKdTree(): trianglesLeft
 wouldn't make sense, as the iterators of the CURRENT node must be set
 to be part of the leaf.
+MathUtils Add: Intersection for 3D Line Segments and Planes (needed for
 bounding box calculation in case a triangles overlaps a splitting plane)
+TrianglesVerticeRefs Add: clip()-method, calculates left and right AABB
 of overlapping AABB.
~TrianglesVerticeRefs Fix: I mixed up dimensions with vertices count.
 Now fixed!
~Fix FastKdTreeNode: setLeaf didn't work if value was set to 0 and old
 value was 1, because 1 | x = 1. Clearing the 3rd bit first, solved
 the problem.
+testmain: added simonTest() and few other drawing methods
Merge branch 'fastkdtree-SS13-group1' of https://github.com/happah-graphics/happah into fastkdtree

Conflicts:
	happah/kdtree/FastKdTree.cpp
	happah/kdtree/FastKdTree.h
Forgot some stuff while merging... now it comes! :)