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.

docs/doxygen/overviews/customwidgets.h

@@ -108,8 +108,8 @@ protected:
     }
 
 private:
-    DECLARE_DYNAMIC_CLASS(MySpecialWidget)
-    DECLARE_EVENT_TABLE()
+    wxDECLARE_DYNAMIC_CLASS(MySpecialWidget);
+    wxDECLARE_EVENT_TABLE();
 };
 @endcode