Implement HelpPlugin (3 of 3)

[unode]

This is an attempt to split #226 into smaller PRs, easier to review. This PR should be merged after #323 and #325.

[unode]

I don't think I can get rid of the 2 codeclimate issues without making the code harder to read. @attzonko do you think this is acceptable?

Also I ended up re-merging the two features in one PR as I couldn't get everything to validate and tests to pass in the in-between state and it was becoming too time consuming.

Black was also bumped in this PR as I couldn't run the previous version locally.

[attzonko]

@unode Please check to make sure my conflict resolution in function.py did not break anything for you.

Otherwise I think we can squash and merge this.

EDIT: NVM it did break stuff fixing now

[codeclimate[bot]]

Code Climate has analyzed commit 6c0b55cf and detected 2 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	2

View more on Code Climate.

[attzonko]

@unode Ok I think I fixed the mess :) Can you verify that the commit makes sense to you? https://github.com/attzonko/mmpy_bot/pull/326/commits/f0a703983f8d881823b7ac54fedfb07356d5fa2e

[attzonko]

As all the tests passed, I am pretty sure it is correct, will go ahead and merge.