set longitude/latutude rectangle on the command line
plot: scale to km, to make axis labels more readable
Makefile: select city parameters and file names by variable CITY (default BUE)
add various cities; increase nodes array to 10 M; recognize also subway entrances

That way, at least Madrid seems to work, too.
db.c: read OSM data from file instead of mmap'ing it

The mmap overwhelmed expat when the data set got too large, producing
excessive delays in XML_GetBuffer. (E.g., the London map didn't even
begin to load after ten hours. Now the whole processing takes about
two minutes.)
Makefile: split city parameters to simplify access; fix PAR typo (was AR)
subosm.c: display progress when routing
add "pretty-plot" (to PNG) mode; change yellow to orange, for better contrast
add generation of thumbnails (plot -t)
Makefile: add processing the list of cities; plot: define colors in variables
db.c: also recognize "ways" marked as subway entrances as subways

For example, a few stations in Vienna use this.
Makefile: complete Web build; remove some empty south from the BUE data set