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/dragimag/dragimag.h

@@ -64,10 +64,10 @@ protected:
     wxBitmap    m_background;
     bool        m_useScreen;
 
-DECLARE_EVENT_TABLE()
+    wxDECLARE_EVENT_TABLE();
 };
 
-DECLARE_APP(MyApp)
+wxDECLARE_APP(MyApp);
 
 #define TEST_USE_SCREEN   100