Lighting

[Robadob]

Adding lighting support will need to include:

• Add a usable lighting class, with usage similar to the style of the existing entity class (probably a general class, with subclasses for the various light styles).
  • Pass lighting details to shaders
• Parse mtl files somewhat properly (not sure if we want to go as far as separating faces into groups, each with different mtl properties)
  • Add material details to model export/import
  • Pass material details as a uniform struct to relevant shaders
• Integrate lighting with all existing stock shaders

[Robadob]

Most of this will be covered by the assimp branch. #26