#8294 Style @username within editor
From [#8282] https://forge-allura.apache.org/p/allura/git/merge-requests/327/
might be nice to style @foo in the editor, like links are blue and underline. Just a visual helper, not an actual link unless you click preview. However this might be quite hard or not practical, as it would rely on the codemirror markdown parsing to tokenize @foo so it has a span & class of its own.
Also our version of codemirror isn't up to date, so probably would be best to update it first, to make sure any deep customizations work with latest.