Bugfix: EDA_RECT to BOX2I generated wrong boxes

The "operator BOX2I() const" of EDA_RECT produced
wrong boxes, usually much to big. It passed its
end-position as second argument to the constructor
of BOX2I. However, BOX2I expects its size as second
argument.

This caused a dramatic performance penalty in some
cases.

include/class_eda_rect.h

@@ -227,7 +227,7 @@ public:
     {
         EDA_RECT rect( m_Pos, m_Size );
         rect.Normalize();
-        return BOX2I( rect.GetOrigin(), rect.GetEnd() );
+        return BOX2I( rect.GetOrigin(), rect.GetSize() );
     }
 
     /**