examples: Add the ability to debug graycode with out camera, add crosses indicating decoding accuracy
examples: Add the ability to debug graycode with out camera, add crosses indicating decoding accuracy

Using 'v' will put the images direct from the generator back into the decoder.
Then show the decoding results. All going well a gradiant image from black to
white is expected. Crosses in red are where points should align, crosses in blue
are the actual values detected.

WearableComputerLab/LibWCL,WearableComputerLab/LibWCL,WearableComputerLab/LibWCL,WearableComputerLab/LibWCL