Improved door editing

[ConConner]

Current door property window is a bit unintuitive and, like a lot of other old menus in MAGE, could use some redesign to more tightly integrate with existing editors.

Ideas for it:

• Rename "auto link", "auto setup", "link only" to better resemble what they do
• If a connected door is found, open a side panel with the other door open in it
• Between panels there is a button that can toggle between something like "Linked", "Manual" and "Mirrored" mode -> "Auto Link" checkbox would no longer be needed.