Refactor Submap_pool::clear_submaps() (remove a duplicated code block) and add debug messages if (TESTING_MODE).
Add a (potentially-randomized) display name to Mapgen_spec.  This way we can give the player more information on what a particular map is supposed to be.  For example, a mall tile called "mall" isn't very helpful; but if we call it "Bill's Clothing Outlet" it gives the player a LOT more information.  Useful both tactically and for improving immersion.