• Improvement: made use_peeringdb an attribute of devices' declaration.
• Improvement: some fixes.

Also, the tool can be used as a library now.

• New: IP based filters extended to the use of prefixes too.
• New: --use-peeringdb argument to fetch missing peers' ASNs from PeeringDB (e.g. in case of multi-lateral peering at IXPs).

First release.