Improves in emacs:
- use htmx to send content to the controller
- show txt and formatted_txt content in the second panel
- show two tabs if "tabs" winix parameter is used
- add an option to show either one or two panels
- correctly resize the editor window (F11) when two panels are shown
Improves in ckeditor:
- use htmx to send content to the controller
- do not check automatically for ckeditor update
Improves in tinymce/nicedit/meta/env:
- use htmx to send content to the controller
while here:
- change PascalCase to snake_case in meta/env controllers
- update CodeMirror editor to 5.65.16
- udpate Showdown (markdown to html converter) to 2.1.0
