#pragma regions and folding and unfolding

[TechnicJelle]

Is your feature request related to a problem? Please describe.
Given that PGEtinker only supports a single file, it would be nice to have more tools to organise it and bring order to it.

Describe the solution you'd like
As such, I propose proper support for #pragma regions, and folding and unfolding for them.

I have a couple utility functions that I'd like to fold away here:

Describe alternatives you've considered
I've not considered anything else, yet.

Additional context
N/A