Improve design

[magsout]

What I had in my thought:

The toolbard is separated in three.

1. button list of action: reduce, beautify, refine on the left and a new dropdown for the list of checkboxs (Include thing)
2. the checkbox of iframe
3. a new dropdown with the list Send to * of actions

@wisniewskit @karlcow ?

[karlcow]

I even wonder if the show iframe should be visible most of the time. And maybe the title is not intuitive.

Is it in fact something like "Testcase preview".
So probably there should be a switch which split the window in two, only we select Testcase preview.

[karlcow]

and because I didn't say it but yes to everything else.

[wisniewskit]

Just FYI, I'm currently thinking of replacing the main textarea with a split HTML/CSS view like JSBin et al have, as karlcow suggested. I would also add an option which generates a final testcase as plain HTML and places it into the clipboard (or something along those lines). In the future we could also add a second "generate" option for making a web platform test instead, if that's feasible.