Currently the interface for editing messages is limited to a
command-line API tool; it's great for testing with e.g.:
./api/examples/edit-message --message=348135 --content="test $(date +%s)" --site=http://localhost:9991 --subject="test"
The next commit will add a user interface for actually doing the editing.
(imported from commit bdd408cec2946f31c2292e44f724f96ed5938791)
