FF1 conservative bug fixes

Description

There are other comprehensive bugfix patches out there, but they also make aesthetic changes. This one fixes the bugs while preserving more of the nostalgia. This patch fixes 18 simple bugs. It also addresses 3 issues that are more debatable and open to interpretation. Namely, the wonky scheme for Magic Defense increases on level up, the poor shuffle algorithm for determining turn order, and what to do about the unused Intelligence stat. Finally, it makes 5 convenience fixes (respond rate default, no more party re-sorting when poisoned, multi-item buying, multi-item using, and displaying Magic Defense on the character sheet).