1. wxLoad/SaveFileSelector return "wxString" instead of "char *"

2. WXDLLEXPORT was misplaced in a couple of places (hopefully my chanegs won't
   break compilation for other compilers)
3. Some VC++ warnings suppressed in socket code


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@1464 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/string.cpp

@@ -80,7 +80,7 @@ static const struct
 } g_strEmpty = { {-1, 0, 0}, '\0' };
 
 // empty C style string: points to 'string data' byte of g_strEmpty
-extern const char *g_szNul = &g_strEmpty.dummy;
+extern const char WXDLLEXPORT *g_szNul = &g_strEmpty.dummy;
 
 // ----------------------------------------------------------------------------
 // conditional compilation