colorize_nicks breaks the surrounding colors

[yardenac]

If the line already looks like this: [yellow]Hello nick nice to see you[/yellow]

And colorize_nicks wants to do this: [purple]nick[/purple]

You end up with this: [yellow]Hello [/yellow][purple]nick[/purple] nice to see you

Instead of just adding a generic color-reset character, it should look at the whole line and repeat whatever color control characters came before it. This is more complicated but more correct.