You need to attach a callback on the variable 'intf-event' of the vlm
object.
 Becarefull, as (always) inside an event callback you cannot call back
the object (here vlm).

 The input variable "program-scrambled" will contain the state for the current
program only. If at least one es is scrambled then the whole program is.
 The associated event is INPUT_EVENT_PROGRAM.
 If necessary for a better GUI support, we could change it to a list.

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.

This could easily be extended to support varaibles of other types, and
set/get operations. But I don't need that :D

It fixes a growing amount of cache as noticed by Sbastien Escudier.

It will allows to remove libvlc hack.

It is also needed for a clean API for libvlc.

It is thread safe (or should be).
No snapshot should be lost.
The image encoding is now done outside vout thread (in the callback).

It fixes a few memleaks in case of error.

(Feel free to move/cleanup)