ADDED FFT analyses.

CHANGED abandon the unpredictable behaviour of the Simulation Command
dialog.  You now separately add simulation tabs (which have invariant
command types once created), and the dialog edits the current tab.

Also a bunch of bug fixes to make multiple simulation plots actually
work.

common/widgets/mathplot.cpp

@@ -1676,12 +1676,8 @@ mpWindow::mpWindow() :
     }
 }
 
-mpWindow::mpWindow( wxWindow* parent,
-        wxWindowID id,
-        const wxPoint& pos,
-        const wxSize& size,
-        long flag )
-    : wxWindow( parent, id, pos, size, flag, wxT( "mathplot" ) )
+mpWindow::mpWindow( wxWindow* parent, wxWindowID id ) :
+        wxWindow( parent, id, wxDefaultPosition, wxDefaultSize, 0, wxT( "mathplot" ) )
 {
     m_zooming   = false;
     m_scaleX    = m_scaleY = 1.0;