Minor code cleanups/fixes
Minor code cleanups/fixes

- Indentation fixes
- Simplified logic in write_topo_files()
- Removed unused test variables
- Consolidated 2 write+tests in write_trc_files() into one.

FR4NK-W/osourced-scion,netsec-ethz/scion,dmpiergiacomo/scion,dmpiergiacomo/scion,Oncilla/scion,Oncilla/scion,dmpiergiacomo/scion,netsec-ethz/scion,dmpiergiacomo/scion,klausman/scion,klausman/scion,klausman/scion,netsec-ethz/scion,klausman/scion,Oncilla/scion,netsec-ethz/scion,FR4NK-W/osourced-scion,FR4NK-W/osourced-scion,dmpiergiacomo/scion,dmpiergiacomo/scion,Oncilla/scion,FR4NK-W/osourced-scion,FR4NK-W/osourced-scion,klausman/scion