Mob AI Tweaks

-Fixed door zombies spawning 1% more common that usual.

-Fixed door zombies still being able to spawn despite their spawn chance is set to 0 in the config.

-Added a hostiles_visual_sit_height_offset config. You can now adjust the visual sit height of sitting hostile mobs. This setting is entirely client-sided.

-Hostile mobs will now check if the boat they are riding is REALLY classified as a boat via tags. This is to prevent them from jumping off of any mount that extends BoatEntity but isn't really a boat (e.g. Create mod train seats) when attacked.