Minor changes to improve IDE stability
Myriad viewport status bar improvements

See #107.

- Moved zoom dropdown and buttons to viewport status bar
- Added icons to image size and mouse coordinate panels
- Made status bar flowable, so panels will adjust their size dynamically
based on content
- Many minor adjustments to size and layout of all components.  To
accommodate the zoom drop-down, the panel had to be slightly enlarged...
something I'm not thrilled about, but the zoom box is already a bit on
the small side, so shrinking wasn't an option.

Still need to test on high-DPI settings, but that will have to wait for
another day...