Remove code that's going away.
Add Icon and Image definitions
Remove commented out code
Update the application, runner script, and layout.

Layout no longer uses shadow constraints.
Remove the need for the enaml.utils module
Remove code which is going away
Whitespace commit
Add the ToolkitObject definitions
Whitespace commit
Fill in the initialize method on Declarative
Properly handle change notifications of type "event"
Whitespace commit
Update the Window definitions
Update the Widget definitions
update imports
Update imports
Update the ConstraintsWidget definitions
Update the Container definitions
Update the Control definitions
Update the AbstractButton definitions