Colored nicknames

[casperstorm]

It's common that each nickname has it's own color, which helps readability.
For picking the colors we should use accent color converted to HSL and then pick a random hue value, while not touching saturation and lightning.

Stretch goals:

• Caching the color to a file with nick@host and invalidated on theme change.
• Enable/disable colored nicks in channel settings (#6)

[tarkah]

I think we can implement without any caching. If we hash nick@host, we can use that as a seed for rng for the hue value and it should be deterministic. Maybe we cache at runtime for performance reasons, but we shouldn't need to persist it to fs

[casperstorm]

Thats a great idea!