GPUTypeFromToGL: Move GPUtype impedance matching code further up.

It also needs to check and possibly fix / reshape() 'gpu' input objects
if a 'tex'ture object was provided for recycling.
GPUFFTDemo1: Checkin some benchmark mods.

Just for benchmarking, not for release.
New demo GPUFFTVideoCaptureDemo: Run FFT based low-pass filtering on live video feed.

To give both Matlab's fft2() and GPUmat's fft2() a could race against
each other.
Both pathways, traditional Matlab and GPUmat CUDA style were optimized
to give their best performance (hopefully). This should be an
interesting race.