A fired moss arrow produces moss blobs, which have two problems:
* they react to water arrows by producing more moss blobs that also react to water arrows, meaning the player can easily create jungles and crash the game
* they do not react to normal water fluids (to prevent the explosion mentioned above)
This should be fixed by making normal moss blobs reacting to STIM_WATER by producing another type of blob that no longer reacts to water.
At the same time, look into making the blobs grow instead of just spawn.
I've left the task of making moss blobs visually grow when spawned until later, since that appears to be less trivial. (The rotation matrix hack should work, but I don't think it's exposed to scripting right now, which means SDK work.)
