- Buttons on dialogs were not getting width and height
- Tooltip buttons were getting standard button spacing when they
should be closer to their corresponding menu button
- Several buttons and other elements had containers just to get
spacing in button sets; rename button-container class to
button-set-item and apply directly to elements where possible.
After moving the padding to the content of buttons, we ended up with
extra padding around text buttons that wasn't there before. The
"Download" bar doesn't look great with no padding at all, but it needs
to match the text buttons so the text doesn't jump to the right when
it switches from "Download" (text button) to "Connecting" (progress bar).
So we pad both text buttons and progress bars just a little bit, less
than a standard button but enough that progress bars look OK.
