Make highlights stand out, re-fix empty message check, make colors seed only get set once, add "/ " as an escape for messages beginning with "/"

A clarification on the last bit: Instead of having to type "./text" or " /text" to prevent "/text" from being interpreted as a command instead of a normal message, this change allows people to prefix "/ " to messages starting with "/" to allow them to be displayed as-is. So typing "/ /text" will make it so everyone else sees "/text" in the chat.
It doesn't affect people who wish to continue doing " /text" or "./text", it just provides another way of doing things, as "/ /" (and "//") are a pretty standard way that IRC clients allow for things like that.