find a way to load clickable netconvert import error logs

[namdre]

errors from importing an osm file can be useful to hunt for problems. There is currently no good way to jump to elements in the log.

• log is only available in netedit when using 'load netconvert configuration' (loading a log file directly into the message window in netedit / sumo could help)
• many error messages are not in clickable format

[behrisch]

loading a log would be the easiest solution