Revert "Prefer std::unordered_xxx rather than versions from tr1,stdext,__gnu_cxx,boost namespaces. Note: tr1 namespace is deprecated in VS2017.5"
Revert "Prefer std::unordered_xxx rather than versions from tr1,stdext,__gnu_cxx,boost namespaces. Note: tr1 namespace is deprecated in VS2017.5"

This reverts commit 77107af3330565a164bc2b85605a8c67850f30c2.

paroj/ogre,OGRECave/ogre,paroj/ogre,OGRECave/ogre,paroj/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,OGRECave/ogre