Added new world generator: Flat

[Senzo]

I can't get this to work. I've edited the world.ini file as stated, however the world gen looks like normal world gen. I've even deleted everything in the world folder except for world.ini then restarted Cuberite so it generates new seed and etc but never see a flat world. How can I get this working as posted? I've toggled the Height from 1 to 7 but always get steep mountain-like terrain.