Toplevel/Application redesign ideas about termkit HOT 1 OPEN

Pending tasks:

• We need a way of notifying a Toplevel that the frame has changed, currently View set _frame behind its back, so there is no way to trigger a buffer reallocation

The redraw method on the Toplevel probably needs to check if the backingStore is still correct? But that might get a clipped region, so it wont be able to paint the real region.

So what is needed is when the size of the Toplevel changes, it needs to have its backing store invalidated, and the view redrawn. And currently this is not the case.

• Probably should not use an [Cell] as the backing store, but instead a proper Layer that wraps the cell, and tracks columsn/rows, just to track the information and enforce the data.
• Optimize: no need to reallocate the buffer if it moves, only if the size changes.

Other things:

• Drivers probably should not expose add (rune) as an API, and instead use add (character) only, as the column tracking is now done in various places, and I do not think it is necessary
• ConsoleDriver should expose a "size" property, rather than cols/rows

from termkit.