add a library for common WidgetDescriptions (e.g. a widget to control x,y,z and rx,ry,rz)

source/ArmarXGui/libraries/CMakeLists.txt

...arXGui/libraries/DefaultWidgetDescriptions/CMakeLists.txt

...s/DefaultWidgetDescriptions/DefaultWidgetDescriptions.cpp

...ies/DefaultWidgetDescriptions/DefaultWidgetDescriptions.h

...i/libraries/DefaultWidgetDescriptions/test/CMakeLists.txt

...WidgetDescriptions/test/DefaultWidgetDescriptionsTest.cpp