Qt: rework of the Sout Dialog

Qt: rework of the Sout Dialog

You can now add any number of duplicate parts you want. You can add them to create a new Tab. You can have two HTTP output or two File output, for example.
Most of the widgets creation and MRL generation part has been splitted from the main class so that people why little knowledge of Qt can understand what is going on.

Expert in streaming can personnalize more easily 'their' part of the UI with derivation of VirtualDestBox and implementing constructor+getMRL()

The huge structure has been removed.
This is a huge change in this dialog, but I think the old one was beyond possible repair.