Fix texture loading for materials with more than one texture.
Choose lightmap material if more than one texture is set in a material. Other material types have to be deduced from other things, not sure about this yet.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3633 dfc29bdd-3216-0410-991c-e03cc46cb475