Add an array of arguments to isReadOnly() method of actions, to let
them change their results depending on what actions are called.
Primarily used by the 'api' action. Ideally in the future that will be
multiple actions. But this might still be useful.
Broke up the tag action into two different actions (publictagcloud and
tag). Brought it up-to-date with the new framework, but haven't fixed it
for phpcs yet.
