[request] navigation between folder expand level

[robertlzj]

Current, could do some navigation editor-keyboard-shortcuts, and support "word/paragraph' unit.

I think navigate based on folder (Fold/Unfold) is usefull.
The script is organized by control statements rather than line breaks.

For example, Ctrl Up/Ctrl down to navigate to the start/end position of current folder scope, like start/end of current if-end, next nearby if end with same level, etc;
Ctrl Left navigate to the upper level such as function end.

And, seems it associate with folder level excatlyt.