Mega patch to introduce the new 3-d interface (to be described later).
The new interface has been tested with both X3D and OpenGL under Linux.
Being tested under Windows.
Note that several changes are expected in these classes (OpenGL in particular)
in the coming days.


git-svn-id: http://root.cern.ch/svn/root/trunk@9665 27541ba8-7e3a-0410-8455-c3a389f83636