simplify and fix light computation
Added index buffer to Pyramid creator
primera versio del obj-loader; sols per models amb vn
Always use colours, even if we have to invent them
now computes normals (per face) when the model has none.
dertails to handle missing .mtl
Changes  to load objs...
added several models, and code to switch easily
fixed for running condition w. materials load
Merge pull request #2 from alvarv/fixDia1

Fix dia1
Merge pull request #3 from alvarv/modelsOBJ

Models obj