Merge branch 'bug-8481-use-qobject-cast-for-tweaklets'
- bug-8481-use-qobject-cast-for-tweaklets: Use RTLD_GLOBAL in dlopen() for plugins with gcc < 4.5 Use the current CTK master in MITK superbuild. Redesigned BlueBerry tweaklets to use qobject_cast. Fixed sorting algorithm in case of unmet plugin dependencies.