Merge branch 'bug-15852-u4-platformproject_enable_easy_conversion_of_datatypes' into bug-15852-u5-platformproject_enable_easy_conversion_of_datatypes
Conflicts:
Modules/QtWidgetsExt/QmitkHistogramJSWidget.cpp
Also fixed some incompatibilities which came by search/replace from mitkIndex3D to
itk::Index<3> (when index was in vector, oftentimes two >>).