Patch 2.1.9

• Fixed layering issues between swimsuits and other underwear

Modding API changes

• The behavior of the mandatory property in item categories has been modified: It still exists, but as the logic wasn't working properly, it is no longer used by BondsSession#setItem() to ensure the presence of underwear. A new BondsSession#_ensureUnderwear() function now takes that role.