don't transform the edges of a triangle during a rotation/shifting - they are re-calculated afterwards anyway
 * this should improve the performance of model transformations significantly
fixed the order of the vertices for OpenGL: a counter-clockwise order is expected


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@711 bbaffbd6-741e-11dd-a85d-61de82d9cad9