Added minimap script using GUI texture icons

I created a script that places icons on the overhead map discussed in Issue #85. It uses GUI textures of the flag, player, and ball icons discussed in Issues #111, Issues #119, and Issue #110, respectively. It uses the current overhead camera, but could be modified to use a raster. It requires transforms for the ball, player and flag. It also has a player color input, which tints the player and ball icons.