Changes are required for the old version of libg++ which does not support:
* std::wstring
* locale
Changes include:
* #if/#endif removal of code which won't compile.
* Addition of a xerces_string_adaptor which doesn't need locale.
* Addition of typedef "base" referring to basic_XMLReader.
* Extended use of member typedefs to simplify code.
* Added xerces_initializer class to call XMLPlatformUtils::Initialize() and
XMLPlatformUtils::Terminate(). This avoids nested calls to Initialize()
and Terminate().
* Addition of xerces_string_adaptor which converts XMLCh to wchar_t and
back.
* Fixed adaptors to pass XMLCh to Xerces methods rather than wchar_t.
* Added '&' to member function references in ErrorHandlerAdaptor.
* Fixed IStreamAdaptor and InputSourceAdaptor to extend Xerces
BinInputStream and InputSource respectively (were extending Arabica ones!)
