Added --use-stl to cnfigure, wxUSE_STL to setup0.h

  Added --use-stl to cnfigure, wxUSE_STL to setup0.h
  Moved wx/datetime.inl contents to wx/datetime.h and removed
inline redefinition hack.
  Implemented STL-like interface on top of wxList/wxArray, when wxUSE_STL=0.
  Implemented wxList-like and wxArray interfaces on top of std::list and
std::vector, when wxUSE_STL=1.
  Added arrstr.h, moved wxArrayString declaration there; string.h
#includes arrstr.h only if WXWIN_COMPATIBILITY_2_4 is enabled.
  Added WX_CLEAR_HASH_MAP, WX_CLEAR_HASH_TABLE, WX_CLEAR_LIST macros,
to clear a wxHashMap, wxHashTable, wxList containing pointers: deletes
pointers and makes container zero-sized.
  When wxUSE_STL=1, wxStringList works like a std::list<wxString>.
  Made wxBase compile when wxUSE_STL=1.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@21768 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775