makes getMin() and geMax() constant functions

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
a little bit of refactoring and fixing in vec3D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
refactoring Vec3D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
adding lots of comments

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
started testing Vec3D

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>
adds Vec3D to the Testsuite

Signed-off-by: Marcel Schwittlick <marzzzel@gmail.com>