Merge pull request #1 from rlofc/master

update
removed unnecessary files (they are in res/shaders/ )
Create camera if scene doesn't have one.
Selection selects nearest model.
Adds support to load models from different directory and with .gpb/.scene extension.
Examples:
 scene-viewer castle         // loads res/castle.gpb
 scene-viewer castle.scene   // loads res/castle.scene
 scene-viewer models/castle  // loads models/castle.gpb
tabs to spaces
Merge pull request #7 from bosoni/master

adds: create camera. select nearest (or none). load .gpb/.scene from different directories.