Use base 36 when generating message IDs, gives us full 0-9a-z to use while preserving uniqueness nicely

irc/server.go

 func (server *Server) generateMessageID() string {
 	// we don't need the full like 30 chars since the unixnano below handles
 	// most of our uniqueness requirements, so just truncate at 5
-	lastbit := strconv.FormatInt(rand.Int63(), 16)
+	lastbit := strconv.FormatInt(rand.Int63(), 36)
 	if 5 < len(lastbit) {
-		lastbit = lastbit[:5]
+		lastbit = lastbit[:4]
 	}
-	return fmt.Sprintf("%s%s", strconv.FormatInt(time.Now().UTC().UnixNano(), 16), lastbit)
+	return fmt.Sprintf("%s%s", strconv.FormatInt(time.Now().UTC().UnixNano(), 36), lastbit)
 }
 
 //