improve behaviour if typekits are not build

Better fallback strategy to show at least camera images and the
StructViewer even if typekits are not build at all
Changed include order of header, for xenomai systems.

xenomai uses Class signals in her headers, unfortunately qt seems
to have a #define signals protected. Therefore signals is a reserved word.
We now make sure that we first include the headers that include xenomai,
and afterwords include the QT-stuff.