Solution: remove the EntityAISwimming. After testing, I determined that entities can go walk up and down in water if their step height is at least 1.0F -- besides, stone doesn't float.
See #23

@sky0-1 The AI is not implemented in the angel class. See https://github.com/TheTemportalist/WeepingAngels/blob/master/src/main/scala/com/temportalist/weepingangels/common/entity/EntityAngel.scala#L40
Ill have to look into this though because I thought this was fixed earlier.