qdoc gets confused by QtConcurrent namespace and QtConcurrent module

There is a C++ namespace named QtConcurrent, and there is a Qt module named QtConcurrent. qdoc must be modified to keep track of both of them. e.g. a member function should be a child of the namespace but only a member of the module. That is, the member function's parent should be the namespace, not the module.

This is further complicated by the inclusion of each member function in a header file, and these header files are also documented.