can.ui.Modal API

## Purpose
- positions content in an area within some element / frame
## Learn from
- http://jqueryui.com/demos/dialog/
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## Options
- enabled / disabled - what would this do?
- autoShow - show right away (defaults to true), but allows you to call show / hide later.
- hideOnEscape
- hide - effect to use, can be a function
- show - effect to use, can be a function
- modal / block - adds a block behind it
- position - (should work with positionable)
- of - which element the modal is added to
- zIndex
## Events
- show / hide (probably preventable with preventDefault)
## Methods
- show / hide
- moveToTop
## Theming
- overlayClass?
## Examples
### show how to close w/ buttons
### show how to drag
### show how to make stacked modals
### prevent close via async events ...
## Notes
- esc to hide the overlay?
- open / close vs show / hide