Feature BiRB

[jordanh6]

This PR primarily adds the code for running Binary RB (BiRB). Notable other changes:

• RandomizedBenchmarking and SummaryStatistics classes have been modified to support BiRB's data type ('energies')
• Added tutorials for BiRB and MRB with universal gate sets

[coreyostrove]

Hey @jordanh6 , great work!

Regarding the failing unit tests, this is due to the installation failing on newer versions of python. This is a related to a dependency bug (not of our own doing) that was fixed in the latest release. If you merge 'develop' into this branch that should fix that issue and get the tests at least to the point of actually running again. Let me know if you'd prefer me to do so on your behalf.

[coreyostrove]

There looks to be a change in ibmqcore.py (commenting out an IBM backend related check) that might be a holdover from some testing you were doing. Is that change intentional?

Great work on adding detailed docstrings throughout the new code. There are a couple of new methods that were added to the SummaryStatistics class in vb.py, avg_energy and outcome_energy, which are part of the public facing API but are currently missing docstrings, so adding those in would be useful. I also noticed that while most of the new functions added in randomcircuit.py as part of the private-facing API (i.e. with leading underscores) had comments associated with them describing their inputs, outputs and purposes, a couple of these functions didn't. While this is in my opinion more of a 'nice to have' than 'need to have', future you and us will undoubtedly be grateful for their inclusion.

Elephant in the room now (I'll save @sserita from having to be the bad guy this time around), we need to add some unit testing for these new modules. This can be a bit confusing the first time around with needing to understand the syntax/modules used for testing, but once you've made some once it isn't actually so bad. I'd be happy to go through this process with you and help write these new tests.

[jordanh6]

Thanks! Also, thanks to @dhothem for writing a large portion of the code and documentation.

I think I resolved everything except writing unit tests. I'll happily take you up on your offer to help @coreyostrove !

• Megred develop into feature-birb
• The commented out IBMQ bit was leftover from debugging, so that's been undone
• Added more docstrings.

[coreyostrove]

With the new unit tests added (including some bonus ones extending our coverage for other parts of the RB codebase) and the last couple changes to the code addressing some edge cases from @jordanh6 this all looks good to me.

[sserita]

Thank you both for your work on this, I think it looks great! Really appreciate the unit tests and tutorial updates! :)