Add new Tyr and Baldur host keys
Use tput for all color definitions

Using tput means I don't have to do mental gymnastics for escape codes, and if
I ever used a terminal with different escape codes (highly unlikely), it should
still work. I also added some fixed host colors for common hosts to avoid color
collisions.
Add non-FQDN hostnames for hosts in .local to known_hosts
Remove Idunn and Forseti host keys

These hosts have been renamed/removed.