added ipython display hook for improved behavior in the ipython notebook. restructured management of fig/axes
minor fix for backwards compatibility
activate SVG rendering
fixed string escape problems
rename size to figsize to avoid name space collision. minor code cleanup
avoid mutable default values
pep8 fixes
Merge pull request #91 from jrjohansson/bloch-updates

Added IPython display hooks. Added optional keyword arguments to the constructor of the Bloch class. New function Bloch.render that can render the Bloch sphere in given fig/ax instances, or creates it's own if not supplied. make_sphere now dispatches to this function. Minor backwards incompatibilities in name changes of some attributes (size -> figsize) but no major API changes.