GaussianKernel: Remove the assignment operator.
CompositionObject: Implement copy constructor.

Current design is error-prone. We don't even copy m_colors array. And if
one use default copy ctor m_pRLEData was also not copied.
CMouse: Remove the assignment operator.
Don't shadow class member.
MainFrame: adjust auto-zoom logic for DVB.

We can't determine whether event is triggered after channel change or on
resolution change. Always restore default auto-fit factor.
MainFrm: Prevent window from moving when scale factor is too low to fit video.