Fixed segfault while opening MS OOXML documents.

Fix for this problem: !111 (comment 946260). In short, on Qt5 we used QSet<T> QList::toSet() which worked as loop with index. Now we are using constructor with iterators: QList(InputIterator first, InputIterator last) which iterates our values() and here we have a problem. We are using iterator on temporary container, that causes our crash. It is enough to pass iterators of our custom QHash (DrawingMLColorScheme) to constructor.