This replaces the ace editor with the monaco editor. It fixes quite a
few small paper-cut bugs and should be easier to add code completion
to in the future.
Many of the snippets are omitted but can be added back later if needed.
Otherwise, we have tried to preserve the existing look and feel as much
as possible.
The notification reducer should decide when to display notifications rather than having notifications scattered throughout the code.
Also start using translations so that user-visible strings are not scattered in code.