Add more python file extensions

[augustelalande]

Add more python file extensions. Namely .ipynb for jupyter notebook files, and .pyi for stub files.

[augustelalande]

Just noticed jupyter notebook is a seperate entry. I also didn't realise jupyter supports more languages than just python (although I think python is still the most common). Anyway it would be nice so support the python ignores in jupyter, although I'm not sure how you guys want to structure that.

[epage]

Let's split jupyter out to an issue to discuss how that should be handled and then we can move forward with pyi immediately

[augustelalande]

Sounds like a plan

[augustelalande]

I removed the ipynb extension, but after giving more thought I don't feel strongly that the python specific dictionary should be used with the jupyter notebooks. In short, I think false negatives are worse than false positives.