give each mc client a destination number when connecting

serverCommunication/minecraft.go

@@ -322,9 +322,9 @@ func GenerateDestForNewMinecraftClient() int {
 func isDestInUsageFromOneMinecraftClient(dest int) bool {
 	for _, mcClient := range cache.MinecraftClients {
 		if mcClient.Dest == dest {
-			return true
+			return false
 		}
 	}
 
-	return false
+	return true
 }