Separate Primary GL Context and visuals canvas

Can now create multiple GL canvases with shared context

src/AppFrame.h

@@ -3,6 +3,7 @@
 #include "wx/frame.h"
 #include "PrimaryGLContext.h"
 #include "SDRThread.h"
+#include "ScopeCanvas.h"
 
 // Define a new frame type
 class AppFrame: public wxFrame {
@@ -19,7 +20,7 @@ private:
     void OnNewWindow(wxCommandEvent& event);
     void OnIdle(wxIdleEvent& event);
 
-    TestGLCanvas *canvas;
+    ScopeCanvas *canvas;
     SDRThread *t_SDR;
     IQBufferThread *t_IQBuffer;
     wxCriticalSection m_pThreadCS;