Add more weighted logic

[initsu]

This changes drop item room shape selection a bit. Instead of them being guaranteed to be put first in the shuffle, they are now given 6 times higher chance of being put first. So good odds, but no longer guaranteed.

With that change I'd probably bring Random Walk drop chance back up a bit, maybe to 11-12%.

[Ellendar]

The issue isn't with drop item rooms, when I ran statistics, even with the existing setup they appeared less often than almost every other shape. The issue with the high drop rate is that the combination of a high number of drops and the inescapable drop prevention makes drops vastly better than any other option when hunting for a boss, and especially in GP. If drops are rare this is ok, but right now the fastest way to do almost any GP in random walk is "stick to the bottom and hunt for drops". I'm fine with that being a sometimes thing but not it being all the time. Ideally random walk drops appear at about the same frequency they do in other palace styles. Likely that value is actually lower than 8%, but I want to do more testing.

[initsu]

I think they both are issues. As it is, if you see a non-item drop room, you know that all item rooms must be drop rooms (or that room could not remain itemless).

[Ellendar]

I added the parts of this I want to change. We can revisit item room selection later since I'm not happy with the current solution or this one. Functionally, the goal of making item room shapes appear approximately equally while not leaking information about what directions do/do not lead to item rooms seems impossible (especially as we reduce drop rates). Maybe the best solution is to return to digshake's original solution of just categorizing rooms by entrance type and selecting a random entrance type (though with a fix in place to make rooms with multiple entrance types not have increased chance to appear)