Make "bounding box" as a parameter

[vsimko]

Expected behaviour

It should be possible to use existing OSM data e.g. from http://download.geofabrik.de/europe/germany/
I'd like to use at least the whole city of Karlsruhe since we have a thermal flight covering KA+surrounding area. The region should be configurable by the user e.g. when running the preprocessing script.

Actual behavior

Currently, only a small area of Karlsruhe is used, which is hard-coded in the java source code.