updated expression_tree_tranform to work with lists as well
Merge pull request #5 from eunjongkim/master

updated sympy_quantum_extra.py
Merge branch 'master' of github.com:jrjohansson/sympy-quantum-notebooks
updated notebooks to use sympsi
changed to sympsi
updated urls
added notebook on semiclassical equations of motion
added a table-of-content notebook
fixed some typos
reran notebook