added tooltips and helpUrls

[grintor]

I have populated the helpurl and tooltips for a bunch of the blocks. The tooltips are pulled mostly from the first sentence of the links that the helpurl points to. The helpurls are all from the official python 3 documentation. This makes it easy for users unfamiliar with the syntax to figure out what's going on. Easier, I would say, than if they were working with non-block version of the code, which is pretty cool

[acbart]

Oh hey, this is great! I'll definitely be accepting this pull request. Thanks for contributing!

My only desired change is to extract out the Switch statement work in ast_Call.js into a dictionary that we import. That file is already pretty long and complicated, and that's more "varying data" than "varying control flow". If you're up for the change, please do so - otherwise I'll find some time next week to make the change myself.

[grintor]

Thanks,

I think you will need to be the one to make the changes because I have had trouble getting any version of blockmirror to compile, so can't actually test this PR. I am confident that the changes here are superficial enough that I didn't break anything, but any more complexity and I would be concerned. That said, do you have any guide on compiling this? I think there might be a dependency that needs to be an older version somewhere, it's been a while since I tried, so I can't remember the error I was getting.

I have been just using the release dist, which thankfully has not been minified, so I have been able to work on it without needing to compile yet.