FormulaGrader comparer key

[ChristopherChudzicki]

Resolves #30

• [x] implementation
• [x] tests
• [x] docs
• [x] zipfile, version number, and changelog

[coveralls]

Coverage increased (+0.004%) to 99.907% when pulling f01df3eb3fdbe9f7eada99f705e308ef5e4a4dd2 on formulagrader-comparer into 3a43a036fd0f8bbcfd8e3c82f1807515b749ea97 on master.

[ChristopherChudzicki]

@jolyonb This is ready for review.

I refactored a few small things in FormulaGrader to increase readability, and would like to refactor a bit more as described in #33

[jolyonb]

This looks really good. I like what you've done here! I've littered some comments throughout the code as one-liners. One extra thing I'd like to see is to add an example of this in action to the edX code.

[ChristopherChudzicki]

@jolyonb I believe all comments are addressed now

[jolyonb]

Do we want to add an example of this to the edX example course? This is kind of a big feature. (We can also do that through a separate PR if you desire.)

[ChristopherChudzicki]

Good point. I'll update the course and make the zip, etc

[jolyonb]

Two more things for the changelog - integralgrader works with complex integrands, and tensor expressions have had some bugs fixed.

[jolyonb]

Finally, README.md has a version number in it.

[jolyonb]

Ok, looks good to me! 😃

[jolyonb]

Can you update the Edge site/close appropriate issues?

[ChristopherChudzicki]

@jolyonb OK, I'm going to import the course on Edge then. (I had been using my own course for testing)