Sensible Potions and Poisons

This mod gives some less useful potions and poisons a boost in effectiveness, to possibly bring some variety and options to gameplay. Poisons are now more noticeable, but Poison Resistance potions are more effective as protection and last longer. Poisons also have a slightly longer duration, which means Cure Poison potions and spells have more use. Several utility potions like Light and Nighteye may now be a more valid option at an affordable price, too. Some minor tweaks were also made to how potions appear in loot, mostly to have Resist potions come up in addition to Cure potions.