Code formatting

[mfherbst]

@pbrehmer Some things I noted. Will keep updating as I go through the code.

• I'm a big fan of whitespace between functions. This includes an empty line before the docstring that belongs to a function.
• Line length: In the docstrings and docs you don't care about line length, but for me this applies to everything. Including docs and comments.
• Two spaces before #
• Sometimes when calls don't fit on one line your formatting is quite verbose (one arg per line). I'm not sure I agree with that.
• I don't like line breaks like

  h = AffineDecomposition(
   [basis.vectors' * matel * basis.vectors for matel in ΨHΨ], H.coefficient_map
  )

  where one might as well do

  
  h = AffineDecomposition([basis.vectors' * matel * basis.vectors for matel in ΨHΨ],
                        H.coefficient_map)