Sulphur ore generation

There's a lot of tweaking I'd like to do, but I think this is a pretty good result for a first try.

I tried using WorldGenMinable to generate the clusters of ore, but it had a habit of spawning 6-7 blocks away from the lava.

I'm not quite game enough to put in the configuration options myself yet as I'm still trying to get a feel for your coding style before I try doing infrastructural. I have however declared the configurable settings as variables at the top of the method.
You use ````LinkedList```` here and elsewhere, but I don't think any of the specific features of linked lists are needed/used. ````ArrayList```` would perform better if we don't need to iterate backwards through the lists. Also you might like this syntax for allocating your lists: ````List<T> list = Lists.newArrayList()````. This is provided by the guava library and allows for more readable code. :grinning: