Merge branch 'feature/VertexArrayObjectImprovement' into 'develop'

Allow VistaVertexArrayObjects to store std::shared_ptr to Vertex-/IndexBufferObject.

Allow VistaVertexArrayObjects to manage the  livetime of the Vertex-/IndexBufferObject they use  thorough the use of  std::shared_ptr.
This can be useful to avoid the deletion of Vertex-/IndexBufferObject which are still used by a VistaVertexArrayObjects.

std::shared_ptr<VistaBufferObject> can now be used as aguments for: 
SpecifyAttributeArrayFloat(), SpecifyAttributeArrayInteger(), SpecifyAttributeArrayDouble() and SpecifyIndexBufferObject()

See merge request !23