create application clipboard manager

[tschaub]

To support copy/paste of a variety of Styler related objects, it would be good to have an application level clipboard manager.

A manager would provide an interface for other components to copy/paste. A simple clipboard manager would maintain just a single entry. Other components could submit an object (copy) and check the status of the manager and determine if they could accept the object (paste).

This task is entirely separate from dealing with the client clipboard (see the  Ext forum for an example implementation using swf) and keypress handling.

Until we are dealing with copy/paste between multiple applications (different web pages or entirely different applications) we don't really gain from using the client (or system) clipboard. In addition, we'll probably want to trigger the copy/paste action in multiple places (keypress, context menu, etc). So invoking a copy/paste action should be treated separately.

[tschaub]

As with the color picker manager, this could be implemented as a plugin. When used in the configuration of a styler component (say a ColorField), the manager would provide the component access to a copied object. Need to do some thinking about how to interact with a context menu builder as well.