Alpha - New main layout of the main page (mostly) and parallel downloads

Pre-release of the Smart wrapper branch. Expect lots of bugs/errors if you dare try.

New features:

• Fresh new looking main tab, which provides info on all downloads, pending or not. (Not much for pending ones though... Might just add the video url as info in a later build)
• The new look, lets you have parallel downloads, while keeping things readable! Toggle between Parallel and Sequential downloads with a button in the About tab! The option is saved between runs
• New error messages for you when things do go wrong!

Feedback appreciated, make an issue for it, even if it's not a problem!
Have look at the new look in the smart_wrapper branch readme, there's a neat little gif there.