public class GGVisualizer
A class for visualizing the grid games. Agents are visualized as circles and goal locations
are visualized as square cells. Different agents are rendered different colors. Personal
goals for each agent are the same color as the agent for whom the goal corresponds, except
at a slightly darker hue. Universal goals are colored grey. Walls are drawn either as
solid lines for solid walls, or as dashed lines for semi-walls.