Add the ability to calculate the center of a UIElement
Update the creation of Button, SelectBox, and UIBox
Allow a color for button text
Allow changing the text on buttons
Allow aligning the text on buttons
Change Image's YImage to not be a pointer
Correct part of Rectangle's drawing code
Set the color inside or glBegin
Draw a Quad, instead of a Polygon
Check for null pointers in Arena
Don't bother calling glutSwapBuffers in Arena
Copy *everything* in Button
Allow creation of transparent Colors
Disable the nonfunctional custom destructor for Image
Attempt to rotate the Players based on location
Rectangle::getColor should return a pointer
Simplify Screen::render
Remove extraneous braces in for loops in Screen methods
Simplify Screen::getClickedElement
Copy the entire UIElement