Widget improvements

Add ability to set date in the calendar widget
Add row labels to ButtonGrid.

Integrating images into Image Strings

• fixed a bug in display of graph
• moved image data into python variables (makes pyinstaller easier)

Adding 'Smart' widgets

Starting a small paradigm shift which will simply add Smart to several widgets that usually require a tkinter.variable to associate and watch for changes.

• Removed DropDown in favor of SmartOptionMenu
• Added SmartSpinBox
• Added documentation

Wheel files can be found on PyPi.