+modes, channel key, user limits and its topic. The parameter combination
+<key> and <limit> is optional, as well as the <topic> parameter, so that
+there are three possible forms of this command:
+
+ CHANINFO <channel> +<modes>
+ CHANINFO <channel> +<modes> <topic>
+ CHANINFO <channel> +<modes> <key> <limit> <topic>