collada. collada to geometry - changes to vertex buffers.

Rename vertex array to vertes buffer.
Change vertex buffer binary file prefix to vb. This is preparation to have the vertex buffer be part of a geometry.
collada. collada to geometry - add geometry class.

Add geometry class.
A geometry holds vertex buffers, and in the future additional geometry data.
The conversion process will generate a geometry froma collada file and write it to file in binary format.