ofvbo refactor wip

+ makes all utility methods pass through programmable attribute pipeline
+ makes sure all attributes are cleared when calling ofVBO::clear() - this wasn't the case for custom attributes
+ automatically assigns standard attributes to built-in pipeline when using utility methods or hand-setting attributes
+ unifies execution pathways by following the DRY principle
+ allows for 3d texture coordinates.
cleanup
set VertexAttributeLocation (fixes programmable GL Renderer)
make sure to only activate custom attributes in fixed function renderer.
minor fixes in ofBufferObject

+ GL methods concentrated in ofBufferObject::Data to follow RAII idiom
fix non c++11 evaluation of shared_ptr
whitespace fixes
Merge pull request #3355 from tgfrerer/refactor-ofVbo

refactor ofVbo - ready to merge