Updated TerrainForm to render the terrain twice, using two images to allow cyclic scrolling
Reworked "perlin" noise generator parameters. TerrainInfo now generates a bitmap itself
Can now adjust absolute height range and bumpiness of ground. Control of absolute height range ensures the same vertical range each time, with the same parameters - instead of sometimes getting flat results.
Now places "wobbly ellipsoid" caves
Updated cave generation so that caves should be larger and less bumpy