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/memcheck/memcheck.cpp

@@ -47,10 +47,10 @@ class MyFrame: public wxFrame
     MyFrame(wxFrame *parent);
     void OnQuit(wxCommandEvent& event);
 
-DECLARE_EVENT_TABLE()
+    wxDECLARE_EVENT_TABLE();
 };
 
-IMPLEMENT_APP(MyApp)
+wxIMPLEMENT_APP(MyApp);
 
 // `Main program' equivalent, creating windows and returning main app frame
 bool MyApp::OnInit(void)