Lava/Water Collision Event

Added an event fired when lava and water collide, which would ordinarily create either stone, cobblestone or obsidian, depending on the circumstances. 

By handling this event correctly you would be able, for example, to create your own block on a collision, or stop a block being created at all. 

An example of when this would be useful is for dimensions that add new stone blocks. Handling this event would allow 'cobblestone generators' in that dimension to produce the new stone, instead of cobblestone.

I need this functionality to avoid editing base classes in my mod.