[bugfix] link for subitem not working for knxprod without modules

[olterion]

For knxprod without modules the link in e.g. ParameterRef pointing to the Parameter is not working. (null pointer exception)

[thewhobox]

Module should be null if the item is from the "Main" Module, eg. the direct application.
I think there is a issue before this.
Can you hand me an example ae-manu where this happens?

[thewhobox]

Is this related to pr #48 ?
Does this still happen without the changes from the other pr?

[olterion]

This PR is not only related to #48. There is also this issue, but there is a very simple way to repoduce the error with actual release v1.8.4:

Projekt->Neu->Leer
Applikation->BCU->MV-0012
Applikation Tab->Allgemeines->ParamterRefs automatisch erstellen->deactivate
ParameterTypes->Hinzufügen
Parameter->Hinzufügen->Type->Dummy PT
ParameterRefs->Hinzufügen->Parameter->dummy
Click on link to Parameter -> ERROR "An unhandled exeption occurred: Object reference not set to an instance of an object."

Here is a ae-manu file, where I made this steps:
Parameter_link_error.zip

[thewhobox]

I tested it. Its fixed with pr #48