new function: Code Folding

[XMDS]

If you can hide a certain part of the code, or lock a piece of code on the top of the editor, writing will be more convenient and comfortable. At the same time it will improve the clarity of the code structure, see:#142

[XMDS]

It will be more comfortable to view mian.scm in decompilation............I think most people hate main.scm

[x87]

It's called code folding and unfortunately SynEdit does not support it natively. Adding this feature will be a huge effort and currently I'm not considering investing my time in expanding SynEdit functionality.

I'm also evaluating other options, such as embedding Monaco editor, or even migrate to VSCode.