Rebalance bats

[sem-geologist]

as discussed in #58 this tries to make bats less annoying. These settings looks to solve anoyences with bats. Improvements:

• 1. bats won't spawn in well lit near ground or underground.
• 2. bats now can spawn up to 128 nodes over ground, if there is enough darkness and stonny environment (i.e. spooky castles, dungeons, caverns, dark forests...)
• 3. bats can set home only under poor lit blocks. (no more sleeping a single node above torch)
• 4. bats won't leave guano on well lit floor, even if it would set the home on dark ceiling, this have few positive outcomes:
     • a. protection against guano is moved from protection blocks to lighting the environment - this in particuly is more practical in single-player mode, especially for i.e. long underground rail network, where previously bats would destroy rail with guano.
     • b. in multiplayer it is possible now to set protected dark caverns - makes it possible to have protected guano farms
     • c. light is more intuitive, as that is how bats more less reacts to light in real life.

[EmptyStar]

Seems simple and useful enough, I only worry about removing the protection condition if players might otherwise rely on it to protect their builds from destruction (including guano). I think I understand the value of having a protected guano farm, but I'd like to think of some practical way to accommodate both protection and lighting conditions if possible. Like, could players potentially protect nodes around a guano farm and otherwise allow bats to generate guano in an enclosed and unprotected space?

I'd like to discuss and consider the potential impact of this change before merging.

[sem-geologist]

with this change they can produce guano in protected spaces. Previously if They would want to protect the guano farm (which needs to be not protected itself as would prevent guano generation) they would need to surround it with protection from all 6 sides. With this PR - protection does not protect against bats anymore - light does that. So from that point of view it is much easier to make protected guano farm, as dark (optionally protected from griefers) stony space will attract the bats and needs no additional protection around. If someone wants protection against bats littering they should invest in lights it is more simple and more logic.