Rename pickData -> id.
Start adding per-instance attributes.
Merge branch 'columbusView' into perInstanceAttributes

Conflicts:
	Source/Scene/Primitive.js
Merge branch 'columbusView' into perInstanceAttributes
Merge branch 'columbusView' into perInstanceAttributes
Merge branch 'batching' into perInstanceAttributes
Add per-instance attributes to VAOs.
Start complete re-write of per-instance attributes.
Interleave geometry attributes as part of the geometry pipeline. Remove VertexLayout because it was no longer needed. Revert changes to VertexArray.
Add option to specify which attributes to interleave and made Primitive create separate buffers for per-instance attributes.
Merge branch 'batching' into perInstanceAttributes
Fix after merge.
Compute each geometry's vertex buffers and offset/count in the buffer. Add property getter/setter to change per-instance attributes.
Fix writing to vertex buffer by computing offset in bytes.
Modify vertex shader source if show attribute is available. Move property getter and setter function creation outside of loop.
Fix JSHint warning
Update Sandcastle example to use per-instance attributes
Minor doc updates
Merge branch 'batching' into perInstanceAttributes
Revert changes to GeometryPipeline, Context, and VertexLayout. Add optional parameter to createVertexArrayFromGeometry for already created vertex array attributes.