Properly implement segmented vanilla P5 key room.

[Ellendar]

P5 key room is segmented, and needs to be like the other segmented rooms so it doesn't exit outside.

Also check the GP 1UP room that probably has the same issue

[Ellendar]

This room (and also the drop/1Up room in GP, vanilla room 41) needed to be set up as segmented rooms. Additionally, the existing solution for segmented rooms only actually worked properly because the L7 room drops out. Updated the approach to segmented rooms to work properly.

Specifically, I re-added the system to merge linked rooms into their parent room, which I had removed because it causes issues with the logic. To avoid the issues with the logic (and also because it is more sane) I moved the palace dump to rom into the method that dumps the rom instead of the one that generates the palaces, so the rooms are still split all the way up until the end.