Fixed: CPPanel and popover doesn't close when hitting escape

Previously, a panel or a popover didn't close when the user hit the key escape.
Now it does. The panel or the popover will close on the keyDown event as in cocoa.

Test app in Tests/Manual/CPPanelTest/ and Tests/Manual/CPPopoverTests

Fixed #1767
Fixed: missing bracket...
Fixed: When closing a panel with escape, the delegates are not called

Previously, when closing a panel or popover with escape, the different delegates weren't called.
Now it does.
Fixed: refactoring of the escape feature of the panel and popover
Fixed: removed uelsee import in CPWindow
Fixed: _closeOnBlur in CPPopover doesn't need accessors
Merge pull request #2139 from Dogild/EscapePanel

Fixed: CPPanel and popover doesn't close when hitting escape