Some cleanup work and getting the test application to behave the way
it did prior to the framework changes.
Removed unused directive.
Moved position calculations for alignment and padding to the
ControlHelper class so they can be shared.
Added raw and generated images for the common control icons. They are
not pretty but they do the job.
Added the Checkbox control and refactored some of the support
infrastructure for simple controls.
Updated the test program to show the Checkbox control instead of the
label.
Added event handling support for controls.
Updated test program to handle new event handling infrastructure.
Some refactoring - renamed the TimedEvent class to SimpleTimer.
Updated to change state on release, not on press.
Fixed errors with centering.
Added support for moving and resizing windows (properly).
Updated test program to use the new functionality.
Refactoring the Padding class and the defaults for the application.