GitHub Code Folding

Enable code folding when viewing files in GitHub.

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. --- CHANGELOG --- v0.3.3 - handle multi-level nested blocks v0.3.2 - don't expand previously collapsed inner block when expanding outer block - styling fix that prevented copying code v0.3.1 - remove host permission v0.3.0 - migrate manifest to v3 - update permissions - fix styling v0.2.0 - fix to use CSS selectors from updated github markup - run on bbgithub v0.1.1 - fix missing css file v0.1.0 - remove jQuery dependency - use event page instead of permanent background