Moved tops to a sub packages physics (there will be more Top components each in separate package)
Aded arena class and a few tests.

The commit is raw and rushed.
* Properly tested normnal generation from gradients and adjusted
values to produce the expected results.
* Corrected a bug in GradientTestImage:getPixel
* A few name changes
Removed math.Utils and moved ImageUtils to maths... makes more sense
Implemented Lerp and Bilerp
Work done mostly on the arena,
added code in other classes to support deptha and normal map interpolation
A couple of tiny changes and tweeks (including coments)
ImageUtils is no Utils (once and for all)
Update functions :)
temp... broken