I have now played a little bit with the map-data and came up with a graph which shows all possible connections between the maps, extracted directly from the source so that it is easily updated for newer versions. I tried to use this to create a geographically correct map, but this is not easily done as things overlap, e.g. if you enter a house. Maybe I can come up with a way of drawing this nicely...
Be aware, it also shows any hidden entrance and rooms which may be included in the game.
I did not yet put the source which creates the Graphviz-dot file for this anywhere public, it's only about 100 lines of code, uses the java interface of tiled and other third party libs, ping me if you are interested in taking a look.