Added multi-piece drawing

Added function to draw pieces based on color and coordinate. The expected way to use this function is to iterate over the pieces in the game to draw them on the board.
Unified spacing code

Removed constants from xSpacing and ySpacing and made all settings of the variable the same.
Removed redundant variable definition

Removed some repeated definitions of x/ySpacing and x/yGridMax.
Fixed piece size calculation

Fixed the calculation of the radius of the pieces so they are actually based on the window size.
Move dimensions out of methods

This is the completion of the move of the dimension variables out of the methods and into variables accessible to the entire class. This means each of the variables is now calculated once, rather than every draw pass.