fix #20
* check objio
* add per face normal retrieval in geometry for now
Update AUTHORS
Merge pull request #22 from cgcostume/objio_enhancement_20

fix #20
Merge branch 'master' of https://github.com/cgcostume/cgsee into ogl_3_2_core_basis_14

Conflicts:
	apps/cgsee/painter.cpp
	libs/core/polygonaldrawable.cpp