Re use readonly #12732 #13863

Fixes #18262: interpret languages with empty aliases array as languages that don't want to show up in the picker

New tokens format & theme matching 

Add config setting to control whether alt should show the menu bar

Moving a file over a dirty file with the same name restores the dirty contents of the target (fixes #18291)

This brings in many performance improvements as well as true double width CJK chars.