added ipython display hook for improved behavior in the ipython notebook. restructured management of fig/axes
added ipython display hook for improved behavior in the ipython notebook. restructured management of fig/axes

zasdfgbnm/qutip,cgranade/qutip,qutip/qutip,cgranade/qutip,zasdfgbnm/qutip,qutip/qutip,anubhavvardhan/qutip,anubhavvardhan/qutip