bug#48724: Code collapsing and outline headings for elisp

[Christopher Dimech]

Currently, outline-minor-mode has the capability to treat "defun" constructs
as heading, allowing one to choose to hide some code from view by collapsing
the region of code.  It would be beneficial for the actual major mode itself
(i.e. emacs-lisp-mode) to handle the code collapsing, leaving the code 
highlighting
intact.  Code collapsing could also be extended beyond not only collapsing
functions and variables ((defun, defvar), but also to additional constructs 
that could
be indented (e.g. lists '(...), let, let*, pcase) and other constructs users 
could
find useful (e.g. if, when, ).

And for outline-minor-mode, the mode could then be used to further enhance the 
structuring
of larger chunks of code (e.g. a collection of functions) using outline 
headings.  Outlining
would then be a separate capability different from code collapsing.

Regards
Christopher