[WIP] Forest level with cave

This is my first go at updating the first forest level to include the cave as seen in the show.
![image](https://f.cloud.github.com/assets/4028391/1168894/49a35b0a-20a8-11e3-84af-580046ed4eea.png)

didory123 and I both agree that the tileset needs some tweaking, mostly around the edge of the inside walls to the outside and by the waterfall.

Test it and let me know!