Introduce a Way to Paint Tiles in a Tilemap Randomly

[ChristianGreiner]

Summary

With the new tool you can fill a selected area with random tiles.

Analysis

• We also need a tool to just elect an area which gets filled up with the random tiles. (like the RectTilemapTool)
• The random-mode is toogleable in the TileEditor-View.
• Random tiles could be added by the FillTool, RectTool, OvalTool and maybe the TileBrush.

[ilexp]

I don't think filling an area with truly random tiles would be a useful thing to have. However, making every tool configurable to only paint each normally affected tile with a certain probability could be an awesome thing to have when it comes to quickly creating terrains with a more organic feel to them.

There is already some thought on making the tools configurable in the AutoTile issue #281, which I'm currently working on, and I think adding a randomize / probability option would tie in nicely!