Use wx-prefixed macros throughout the repository.

Change {DECLARE,IMPLEMENT}_*CLASS and {DECLARE,BEGIN,END}_EVENT_TABLE
occurrences to use the wx-prefixed version of the macros.

samples/help/demo.cpp

@@ -273,7 +273,7 @@ wxEND_EVENT_TABLE()
 // static object for many reasons) and also declares the accessor function
 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 // not wxApp)
-IMPLEMENT_APP(MyApp)
+wxIMPLEMENT_APP(MyApp);
 
 // ============================================================================
 // implementation

samples/help/doc/wxExtHelpController.html

@@ -63,7 +63,7 @@ If the documentation itself contains a ';', only the part before
 that will be displayed in the listbox, but all of it used for search.<P>Lines starting with ';' will be ignored.<P>This confuses DOC++, so I leave it out for now:
 <TT>ifdef USE_HELP</TT>: public wxHelpControllerBase
 {
-DECLARE_CLASS(wxExtHelpController)
+wxDECLARE_CLASS(wxExtHelpController);
 <TT>else</TT>{
 <TT>endif