* Embed the app icon in the updater executable on Mac and
use it as the application's icon.
* Transform the application from a background to a foreground app when the
Mac dialog is shown, so that the dock icon is shown.
* Forcibly give focus to the updater application so that the progress window
gains focus when it is shown.
There is a remaining glitch with the application where the icon briefly transforms
back from the app icon to the terminal icon as the application shuts
down. This presumably happens because the custom icon set on the NSApplication
is reset before the dock icon disappears.
