Update top menu bar to be more intuitive.

The back button on the welcome page was confusing, and there were a couple
of pages with no title.
Add in a placeholder app icon.

This is a placeholder icon, but it may stay, unless someone really good at
design comes on board.
Reformat about page, change version number.

The about page was too hard to read, so now it's better. Also, the app is
listed as version 1.0.0 now.