Non-modal dialogs

[gbracha]

Hopscotch does have direct support for non-modal dialogs. One has to construct them by hand. For example, when adding a class or document. In other cases, we simply transition to a dedicated presenter for the dialog. We should make this easier.

We support the web browser's window.alert() method directly, which is modal; this violates a key tenet of the Hopscotch design. It would be tempting to add support for window.confirm() in the same way. This is trivial, but leads to perdition.
Instead, we should support patterns like alert, confirm, and other input dialogs in a non-modal way. A call to confirm might add a banner at the top of the presenter with the dialog (much like the help display is managed today).