This change allows the virtual camera to really output what is in the
program view, some plugin interract with this view but their changes
does not appear on the virtual camera.
Individual sources cannot be used as vcam outputs (yet) due to the fact
that they cannot currnetly scale. If a source is not exactly the same
dimensions as the canvas, there will be blackness on the right and/or
bottom of the source. It's just not currently usable as-is.
Scenes are a much better fit for this because users can transform
sources within scenes as they please to fit the canvas.
At a later point, we'll likely reintroduce this feature as long as
they're automatically transformed or something.
