cppview pure virtual function call fixed

[ewuenf]

I am not too deep into libusb, but the call to

freenect_close_device(...)

in

Freenect::FreenectDevice::~FreenectDevice()

causes the virtual function call. The easiest (and safest) way to fix this would be to make the the callbacks non-pure (whats the deal with pureness here anyway?), like this:

virtual void VideoCallback(void *video, uint32_t timestamp)
{
}

virtual void DepthCallback(void *depth, uint32_t timestamp)
{
}