allow changing fill and outline colors after initialization #25
Description
Currently the constructor is the only way to change fill_color and outline_color of a Button.
The underlying display_shapes objects do have fill and outline properties that allow them to be be changed any time after initialization.
It would be great to have properties and setters to the Button that allow user code to set those without having know about or mess with the underlying shapes objects.
I think it's a pretty natural assumption for users make to think the button would allow this, the issue was first noted on a forum post here: https://forums.adafruit.com/viewtopic.php?f=60&t=174113