It would be useful to be able to iterate over, or return a list of coefficients in PauliSumOp. At present, one has to dig into the details to construct the coefficients for each term. In particular, it requires multiplying

We need to create a Q.History documentation page that is similar in nature to the existing Q class documentation pages. See Q-ComplexNumber.html as an example.

Update installation docs in the /docs folder and on the readme.md

It would be convenient to have a method is_reversible in gate_base which returns true for reversible gates, whose unitary operation is a permutation matrix.