NEWS: Isabelle/VSCode GUI panels

[Makarius]

*** Isabelle/VSCode Prover IDE ***

* The main toolbar provides access to Isabelle examples and
documentation. Plain text files are opened in the editor, but PDFs
require a suitable VSCode extension (e.g. "vscode-pdf" from the
marketplace).

* Output panels for Isabelle Symbols and Sledgehammer, which imitate
Isabelle/jEdit dockables to some extent.


This refers to Isabelle/b42e2dd962a8, but the starting point was 486e094b676c: 
approx. 12 days and 150 changesets earlier.

This integrates the Bachelor project by Diana Korchmar, LMU München. The 
project was intended as an experiment to see if/how Isabelle/VSCode could 
eventually catch up with Isabelle/jEdit. My conclusion: we need a quite 
different approach; imitating existing Scala/Swing GUIs with untyped/unscoped 
HTML/JS/CSS is not going to work --- it leads to unmaintainable self-forks.

There are also fundamental limitations of the underlying VSCode: Electron = 
Node.js + Chromium. That might all be considered "popular" and "modern", but 
it actually feels very archaic to me (funny scripting languages and 
cooperative multitasking from the early 1980s).


	Makarius