Reordering includes to avoid problems on Win32 with VTKQWidget2

This hotfix modifies RendererWidget inheritance. Now RendererWidget
inherits from VTKQWidget2 instead of VTKQWidget.
In VTK 6.3, VTKQWidget2 include somehow somewhere Win32 headers.
This defines the ERROR macro, which creates a conflict with the ApplyStatus enum
(that also defines ERROR apply status).
In order to solve this conflict, #include "Action.h" should be done before
any \#include "InteractiveViewer.h" or "RendererWidget.h"