Removed CTKDICOMCore from pre-load list an generalized look-up code.
Improved pre-load library path handling, fixing MacOS and Windows issues.
Updated CTK containing pre-load library fixes.
Copied pre-load library code from mitkWorkbench.cpp.
QT_LIBRARY_DIR might not end with a slash.
Merge branch 'bug-17956-ctk-library-loading'