This template is not currently used anywhere in CVS apart from the tests. It
is intended to be used in the VTK mark API, and the 2D API. The memory layout
is very efficient and can be used readily with the OpenGL API. So a vector3f[3]
has the same memory layout as a float[9], and using the GetData() function the
underlying storage can be accessed.

Right now this code is confined to one unit test. This may be a candidate to
move to Common once it has received wider testing. It cannot be wrapped.