#7982 Editor should autocomplete artifact references and macros
In the markdown editor, it would be great if you type [ it shows a list of artifact choices. And if you type [[ it shows a list of macro choices. Using the autocomplete addon for codemirror can get us a lot of the way there. https://codemirror.net/doc/manual.html#addon_show-hint
We probably will want to save recently visited tickets, wiki pages, and other artifacts in the browser's localStorage or sessionStorage, so that we can give useful initial choices. We'll also need to do ajax lookups to get a full list of matching artifacts, as well as mount points and project names for cases like [wiki:Baz] or [proj:wiki:Baz].
The UI could be extra nice if it didn't require typing a [ first in some cases, since some people might not know that syntax. If you just typed # it could suggest tickets and put the [ in for you automatically if you select one.