Added anycastcheck.py

The script will fetch which k.root-servers.net instance is seen over
IPv4 and IPv6, and set KML Placemark style according to the check
result. Available styles:

inst4 == inst6 => ok
inst4 == inst6  (both Unknown) => invalid
inst4 != inst6 => nok
inst4 != inst6 (any Unknown) => nok_unk

It does not use the Atlas REST API yet. See
https://atlas.ripe.net/doc/api

Note: Sample KML files should have been commited separately. Can be safely removed from upstream repo