Add UNIX TTY color codes to namespace util::color.
Add UNIX TTY color codes to namespace util::color.

Relates #28.

vast-io/vast,mavam/vast,mavam/vast,vast-io/vast,pmos69/vast,mavam/vast,vast-io/vast,pmos69/vast,pmos69/vast,vast-io/vast,mavam/vast,vast-io/vast,pmos69/vast