Spawn C2ME Fix

This is an experimental and optional release that fixes performance issues with sea life entities:

• Sea stars and sea urchins no longer run a client-side ticker. Their drift and rotation are now calculated on demand from block position and game time, so thousands of ticking block entities are gone and frame times are more stable over oceans and islands. Sea bunnies are unchanged.
• Sea life blocks now cache their render bounding box and the per-variant texture material instead of rebuilding them every frame.

Please let me know if you notice any side effects. I personally experience more stable frametimes around oceans and areas where these entities are placed in a fairly large modpack.