Add a VideoSource implementation based on PCL's Grabber
Add a VideoSource implementation based on PCL's Grabber

The implementation provides a thin adapter of any instance implementing
PCL's Grabber interface.

Clients are expected to inject the Grabber, which is to be adapted
through the constructor of the source. Therefore, all PCL-specific
parameters can be set for the Grabber instance.

mlalic/lepp2,sahandy/lepp2,mlalic/lepp2,sahandy/lepp2