Community Fluid API

Many additions and fixes - consult the commit messages for details. The highlights:

• Additional methods are patched in from IFluidTypeExtension. Look at them
• A lot of support has been added for underwater mobs (nautilus, fish, etc.). Aquariums, race tracks, etc. should work much better now
• First pass at implementing fishing - per fluidtype loot tables supported
• Striders can walk on your fluids (if you override the right method)
• Most of the remaining fluidtype methods now have an implementation. #isWaterLike being a notable exception - some of this behavior is bundled with other things, like #canSwim, and the rest will get their own targeted methods injected into FluidType.