odd grouping of UI components

[pixelzoom]

Related to #259 code review, noticed in #261.

In the Waves screen, when the speaker radio button is selected, the control panel looks like this:

Having the bottom 4 UI components (1 checkbox, 3 radio buttons) grouped together makes them look related, when in fact the Graphs checkbox is unrelated. Consider adjusting the spacing, or add a separator, to make the grouping clear.

[pixelzoom]

Note that decisions made here may impact #283.

[samreid]

Spacing was adjusted in another issue, it looks like this now:

@arouinfar do you recommend further changes to segregate the radio button group from the checkbox?

[arouinfar]

@samreid I like the added negative space. I don't have any further UI changes to recommend, so closing.