as promised, attached is the editor source code. i cant be 100% it's the latest version, but it has all of the map code (converting to both text, and AMOS style draw commands) in it.
I'm not sure there is much 'extra' to learn from it... i did try to create a "standard" input/output file format that could potentially become cross-platform (the .map and .obj files that it creats be substituted directly into the PC version for example) ... however, when i tried to put my new levels into the ST version, it didnt want to run - this may be related to the ST versions copy protection though.
to answer your other PM question MM, i have never created any remake of BW... i have some basic wall-drawing code for AMOS but i didnt write it, and it isnt very good tbh!! (for map/editing purposes your ST/UAE plugins are far better!!)
anyway, hope this helps, and sorry for the delay - kind of been busy of late!!