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/notebook/notebook.cpp

@@ -33,7 +33,7 @@
 // MyApp
 //-----------------------------------------------------------------------------
 
-IMPLEMENT_APP(MyApp)
+wxIMPLEMENT_APP(MyApp);
 
 bool MyApp::OnInit()
 {

samples/notebook/notebook.h

@@ -29,7 +29,7 @@ public:
     bool OnInit() wxOVERRIDE;
 };
 
-DECLARE_APP(MyApp)
+wxDECLARE_APP(MyApp);
 
 
 class MyFrame : public wxFrame