More flexible actions (javascript support)

[jrunestone]

Similar to this discussion I'm often in need of an action for one or more entities that run on the client, not on the server. A prime example is a "print" button for an entity.

Currently, I have a PrintAction that renders a dummy button in its settings. This button is configured to be of a custom property editor type that fetches the current entity id from the URL and opens up a new window with the print view of that entity (via the property editor controller javascript). The user can then use ctrl-p to print it.

Needless to say it's a bit hacky and it only works when you've clicked on an entity, not from the list view. It would be neat to be able to configure client-side actions, that receive entity id(s) for all ActionType..