Gaussian blur shader

Yes, it turned out to be so much simpler to programmatically manipulate the viewfinder shader from the Java-side, specifically from CameraView::onDrawFrame.

Let's implement a Gaussian shader and programmatically program the filter dimensions.

Ok, I now have a programmatically parameterized Gaussian-like filter. Remarks:

• Some thought should go into the logical organization of code,
• Beginning to see some preceivable frame-rate drop from the simple viewfinder.