Refactored Face to remove IFace interfaces
Change Geometry to remove type comparisons on Face
Added default a,b,c(,d) arguments to Face3/4 constructors
Fixed face patching in geometry.dart
Change Ray to remove type comparisons on Face
Add setFrom to Face, mimic new Face hierarchy in RenderableFace and replace Face type tests with face.size tests
Fix Projector and Renderables
Refactored Renderables
Merge pull request #78 from threeDart/remove_iface

Removed IFace and refactored Renderables