Add Code Folding #2195

Code folding - the ability to selectively hide and display sections of a code - is an invaluable feature in many text editors and IDEs. Now, developers can utilize that same style code-folding while poring over source code on the web in GitHub. Works for any type of indentation- spaces or tabs.

ref: https://github.com/noam3127/github-code-folding

This extension has not been maintained for a long time. If it can be integrated into refined-github, it is definitely great.