MiniMap icons added to level_full scene

Same script from closed pull requests #189 and #172. It renders icons on the overview map discussed in Issue #85. This script is currently not hooked up to the level scenes. It should be done programmatically, once the golfball, player and flag GameObjects have known names. Here are the inputs:

// Icons discussed in Issues #111, Issues #119, and Issue #110. Tested with the 512x512 TGA files.
Texture2D flagIcon;
Texture2D playerIcon;
Texture2D playerDirectionIcon;
Texture2D ballIcon;

float iconScale // relative size of the icons on the MiniMap
Color playerColor // main chosen color of player. Default color is red.
Transform flag; // GameObject of the pin/hole.
GameObject level; // GameObject of the current level
Camera mapCamera; // MiniMap camera