-new block called "withered ash", leaves convert into it. it also has falling physics.
-the blob no longer destroys Terrain when spawning
-new mob callad "wither decayer", it spawns around the blob, and coverts some terrain into wither blocks before despawning
-new mob called "the multitude". spawns around the blob, if theres a non-wither mob nearby it will spawn a agoning mob.
-wither bone blocks from blobs now spawn a little bit diffrent to fix a bug where if theres to much lag, the terrain will become covert in wither bone block