Global UI on a bar at the top of the viewport

[LeaVerou]

Depends on: #6

Once #6 is implemented, then edit, save, cancel will all become global, i.e. each will have one button per wysie instance.
As it currently stands, it's very difficult to add any UI to the user's template because of the huge variance between different wysies. The less we change their template, the better.
All global controls need to move to a bar at the top, which will be visible only when its corresponding wysie instance is visible.

List of global controls (assuming #6 is implemented):

• Login/logout/current user info
• Progress indicator
• Edit, save, cancel buttons
• Undo/redo, if Undo functionality #10 is implemented.

Being separate will make styling much easier too, and can actually be a usability improvement in cases of large wysies that span longer than the viewport height, in which case one has to scroll up and down a lot to reach global controls or to see the progress indicator. It is also on par with what many CMSes do, e.g. Wordpress:

Challenges: What to do when there are more than 1 wysies visible on the screen?