started on major revision on expansion search
now _expansion_search works with pauli matrices
implemented the dummy symbol method. Still doesn't work for exp(I*theta) or exp(-I*theta)
removed unnecessary parts and fixed the return of bch_expansion
Added exp(-x) to the flist(sin, cos, sinh, cosh has the same canonical form for f(x) and f(-x) while exp doesn't). Also, added a test in bch_expansion to decide whether expansion_search should look for series expansion in I*x or x
Now works for squeezing operators with real parameters, even with r*exp(I*theta) form. But needs improvement with finding terms including Imaginary numbers. Passed all tests in the notebook
removed debug prints
Merge pull request #4 from eunjongkim/expansion_search

Expansion search