Feat/clean mv layout input

[malmen237]

What does this do?

New default layout

On start the default layout is prepopulated with the sources from the production-setup. The slots that have not been populated is returned empty.

Possible to have a completely clean layout

When box is ticked the layout is cleaned, when unclicked again the default layout is returned into view

Bug-fixes

• When removing sources on running production the multiview will return an empty view with empty label. ID is saved so if the source is added again it will reappear in multiview.
• Restructure of how multiview is updated both on production start and on production.active

[Saelmala]

Left a few minor comments, but some I think are more important, eg. variable name asd