[Firebird-net-provider] Not able to choose Firebird ADO.Net Data provider as data source in VS2015

[Widmer, R. (M&F E. AG) <Ric...@oe...>]

Hallo everybody
I am struggling creating a Firebird connection in Visual Studio 2015. I have a C# class library with which I would like to connect to a Firebird database. I installed these plugins from NuGet:
[enter image description here]<http://i.stack.imgur.com/dR8Th.png>
But when I try to add a new Item "ADO.NET Entity Data Model" with "EF Designer from database", the Firebird connection is not listed:
[enter image description here]<http://i.stack.imgur.com/0o6np.png>
I installed as well the "FirebirdSql.Data.FirebirdClient-4.10.0.0.msi" package from http://www.firebirdsql.org/en/additional-downloads/ just in case an entry in the machine.config file is needed.
The "FirebirdSql.Data.FirebirdClient" reference exists in the Visual Studio project.
The entry in the App.config file is:
<DbProviderFactories>
      <remove invariant="FirebirdSql.Data.FirebirdClient" />
      <add name="FirebirdClient Data Provider" invariant="FirebirdSql.Data.FirebirdClient" description=".NET Framework Data Provider for Firebird" type="FirebirdSql.Data.FirebirdClient.FirebirdClientFactory, FirebirdSql.Data.FirebirdClient" />
</DbProviderFactories>
Can anybody help me with this issue? How can I create a database connection to my Firebird database?
Thank you very much in advance.
Best Regards,
Rico