Add difference highlighting to debug printing

The functions PrintGridRoomHalls, PrintListRoomHalls, and PrintTiles in ExampleDebug.cs will only print if the string generated from the current map is different from the string generated in the previous call of the function. The differences between the previous string and the new string need to be highlighted when the new string is printed. This means changing the font color.

Open ExampleDebug.cs and inspect PrintGridRoomHalls, PrintListRoomHalls, and PrintTiles, including how each stores the previous generated string. Run the existing debug-printing examples to observe the current output; done means changed portions are highlighted by font color whenever a new map string is printed.

Written by the indexing model from the issue text.