+ * (used by QUIT, NICK etc which arent channel specific notices)
+ *
+ * The old algorithm in 1.0 for this was relatively inefficient, iterating over
+ * the first users channels then the second users channels within the outer loop,
+ * therefore it was a maximum of x*y iterations (upon returning 0 and checking
+ * all possible iterations). However this new function instead checks against the
+ * channel's userlist in the inner loop which is a std::map<userrec*,userrec*>
+ * and saves us time as we already know what pointer value we are after.
+ * Don't quote me on the maths as i am not a mathematician or computer scientist,
+ * but i believe this algorithm is now x+(log y) maximum iterations instead.
+ */