Trying to put the texture activation back into setMaterial. This had been changed in early versions of Irrlicht for render state problems. I hope we got them all fixed and can this way make external materials possible again. (problems are all OpenGL only)

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@2900 dfc29bdd-3216-0410-991c-e03cc46cb475