Framerate 0 for capture device

[mynameisfiber]

When using a capture device, this->imgProcSettings.framerate is zero which leads to the Riesz maximum frequency in the UI being 0.

https://github.com/tschnz/Live-Video-Magnification/blob/master/src/main/ui/MagnifyOptions.cpp#L416-L419

This effectively makes this magnification method unusable for capture devices.

[tschnz]

This is fixed now so at least Riesz works on live streams but the Cutoff Wavelength and Frequencies to amplify are not based on the real world anymore see #16