#6 player colors for gtk-client

[Jason Dorje Short]

Some time ago, I remember agreeing with Justin that the
GTK-client should allow you to set specific colors for
chat messages from specific players.

At some point this would be a good feature. Currently
there are only three colors for chats; allowing the
user to specify a specific color for someone on their
"friends" list would make the chat much cleaner IMO.