Improve converter tool GUI

[ra3xdh]

I propose the following improvements for converter tool GUI (accessible from Tools->Data files converter)

• Add possibility to define the library name: Add an option to define the library name for qucsconv qucsator_rf#11
• Add possibility to select data variable from drop-down list instead type-in manually

[tomhajjar]

Presently to create/repair/update a library with the same name as an existing one, the existing one has to be deleted/renamed.

Will Qucs-S now allow overwriting libraries in usr_lib?

Will Qucs-S now allow creating libraries in usr_lib that have the same name as a library in C:\QUCS-S 24.2.0\share\qucs-s\library?

Th reason I ask is the library filename is also embedded throughout the file. Renaming the library doesn't work. You have to replace every filename instance throughout the library.

[ra3xdh]

The mentioned above features are already implemented. Qucs-S allows to create the library with the same file name as existing one, but ask if to overwrite the existing file. The name shown in the library manager is taken from inside the library header. The renaming of the file will not help.

[ra3xdh]

The proposed improvements implemented by #841