Monaco improvements

Fixes #1461 & #1462.

- Restores AceEditor keyboard shortcuts of (Ctrl|Cmd+Shift+D) for duplicating the current selection & (Ctrl|Cmd+Shift+F) for full screen mode
- Fixes support for dragging content (i.e. text links, partials, content files) into the CodeEditor field
- Fixes highlighting paired tokens in Twig mode by bringing in the full HTML mode processing into Twig mode
- Fixes issues caused when swapping between multiple editor instances where editor state (position, selection, folding, history) wasn't being retained across editor disposal
- Minimizes flash of unstyled content when switching between multiple codeeditor instances
- Fixed default "Twilight" theme to more closely match the original Twilight theme used by AceEditor

Author: LukeTowers