reduced the number of slots in bookshelves (#37866)

reduced the number of slots in bookshelves (#37866)

* changed bookshelfs yml

I reduced the number of slots in bookshelves, now it has 40 slots, and since one book takes two slots, and there are 20 fill levels (not including empty) now each book corresponds to one sprite. I also increased the number of books that random bookshelves generate, so that bookshelves will be empty less often.

* increased minimum random book count

in testing there were still a lot of bookcases with very few books in them.

* too many

* still too many

decided it looks better with the variance of having some shelves sparse and some not, rather than all ~half-filled. Wish there was a way to do something about the distribution, rather than pure random maybe something like weighting it toward one of the ends of the scale. but alas, I don't know how to do that.

* guidebook chance is random too now

decided that guidebook chance should also be random. now we can have shelves that are truly empty. anyway, I set it as 0-2, so there is a 2/3 chance that a bookshelf has a guidebook in it anyway, this also means that some shelves will have two guidebooks, but hey; who can have *too many* guidebooks?

* this line shouldn't be here