https://github.com/morphles/fcsgen (link to live program at the bottom)
For now it's just press calculate and then press download to download scenario/sav file. Uses L-Systems as described in readme.
There as hope to use it for GT in a future. Though adding more "flavours" (heightmap generating L-Systems/rulesets), and other features will probably be needed, but I see lots of nice possibilities. So thats it for now