Use wxCFRetain/wxCFRelease in wxCFRef where needed.
Use .get() to access m_ptr of a different wxCFRef instantiation instead of making them friends.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45999 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775