Terrain decorations

I have improved the terrain generator of Teemu with some automatic decoration rules. It's the same kind of style I'm using in Kaduria: first create generic terrain structure, then decorate with automatic growth of features and plants. The new feature in Teemu is that rules are data-driven (related to terrain type) so with one scanning routine you can determine what extra tiles need to be created for that particular tile. The routine is creating things like automatic shallow water edges between ocean and land, and growing bushes next to trees etc. There is a primitive rule to actually remove bushes to avoid them getting too widespread. It's a primitive form of competing from space which I'm going to use in Kaduria in much bigger scale to create plant growth.