Allow empty lines at beginnings of more blocks

[hauntsaninja]

Fixes #4043, fixes #619

These include nested functions and methods.

I think the nested function case can quite clearly improve readability. I think the method case improves consistency, adherence to PEP 8 and resolves a point of contention.

#4060 intended to allow empty lines at the beginning of all blocks (except immediately before a docstring), but missed this case