added more docstrings for ipynbtools module
added more docstrings for ipynbtools module

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