Removes old Qt code, restores the conditional inclusion of the
3Dconnexion license information, shortens the displayed hash, and links
the hash to its repo.
The original License tab used a hard-coded HTML element created in Qt
Designer, which adds style tags to all HTML elements. This commit
replaces that tab with a dynamically-created tab which loads an included
LICENSE.html file at runtime. That file contains no style information,
so obeys the style information provided by the current stylesheet. If
that resource file is not available at runtime, the old license tab is
retained and displayed.
