Fixed errors with math comparison tests.

Fixed errors with math comparison tests. Also, created a single function
for comparing floating-point numbers.
Hierarchy transformation work.
Camera position is relative to parent position.
Light's direction calculated from the game node.

Scene graph hierarchy is used to calculate the direction of each light.
Transform hierarchy finished.

Transform hierarchy finished, although some optimizations can still be
made I guess. For now the solution is ok.
Generic Materials with mapped variables.
Finished engine architecture segment.