Spiders 1.999

Original mod

Changelog:

- Fixed issue with non-AI skeletons spawning in the world.
- Added ability to completely disable or reduce the number of spiders spawning in light.
- Updated build.gradle

This fork will remain on 1.12.2. Asking me to port it to any other version is useless (there are already other Spiders 2.0 forks for modern versions).

Important for mod/modpack developers

The issue that caused non-AI skeletons to spawn in the world is caused by a combination of Spiders 2.0 and Optifine.
I was able to solve this issue. I removed the line
replacement.readFromNBT(entity.writeToNBT(new NBTTagCompound()));
That is, when processing an event and replacing a vanilla spider with a modded one, the NBT data of the vanilla spider will not be passed to its modded replacement. This can be a problem if a mod assigns some important data to the mobs NBT before they spawn in the world.