1) split into wxStringImpl class that has std::string-like API and operates on char* or wchar_t* data and wxString class that provides Unicode iterators and indexes
2) added both char* and wchar_t* versions of many wxString methods to avoid having to use _T()
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45078 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
1. changed c_str() to return wxCStrData (implicitly convertible to wxChar*)
2. added template type-safe wrappers for vararg functions
3. added wxUniChar class representing single Unicode character
4. changed wxString::operator[] and wxString::iterator to return wxUniChar
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@44865 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
