Add "where from" field to door settings

[Diploidd]

There can be many doors an area is accessible from, so combobox add/remove system is required.

[Kauko]

I don't understand this issue. By definitions doors know WHERE you go by clicking on it. Where from you came to a room does not really matter?

Listing all the ways a room can be accessed makes more sense, but this issue does not seem to be requesting that.