Handle dashes in hostnames for Tinc
Tinc breaks if it finds dashes in node names, so replace them with underscores (cf. https://www.tinc-vpn.org/pipermail/tinc/2003-January/000605.html)
Tinc breaks if it finds dashes in node names, so replace them with underscores (cf. https://www.tinc-vpn.org/pipermail/tinc/2003-January/000605.html)