added some docs, added empty copy method to BrainData
added some docs, added empty copy method to BrainData

gallantlab/pycortex,smerdis/pycortex,CVML/pycortex,CVML/pycortex,CVML/pycortex,CVML/pycortex,gallantlab/pycortex,smerdis/pycortex,smerdis/pycortex,gallantlab/pycortex,gallantlab/pycortex,smerdis/pycortex,smerdis/pycortex,gallantlab/pycortex,CVML/pycortex