Add transform= keyword to cbasis integrals (#178)

[msricher]

Fixes #178: Add transform argument to all integral methods; make sure to keep arguments in the same order as original code.

I don't see where transform= keyword is tested in the main Gbasis Python code... @leila-pujal are there tests for this?

Once I add tests, it can be merged. I made sure it still runs and passes, at least. I just want to make sure I can replicate any existing tests.

Checklist

• Write a good description of what the PR does.
• Add tests for each unit of code added (e.g. function, class)
• Update documentation
• Squash commits that can be grouped together
• Rebase onto master

Type of Changes

	Type
✓	🐛 Bug fix
✓	✨ New feature
✓	🔨 Refactoring
✓	📜 Docs

Related

[leila-pujal]

@msricher, yes it is not obvious to find where the transformation is applied. So the transform is used in base_one.py, base_two_symm.py and base_four_symm.py. Basically it is used when construct_array_lincomb method is called for a specific type of base integral (1, 2 or 4 contractions). I think the functionality is tested for both, higher API functions (for example passing a transfrom to overlap_integral) and for the construct_array_lincomb() methods defined in the different base_*.py modules. Let me know if you still have doubts about this and thanks a lot for working on this.