Extend data surface

[tom-p-reichel]

QR code should now contain information about the screen dimension, then data should be stored in pixel data around the qr code.

Try to use the entire RGB color-space for maximum bandwidth.

Since screen colors and cameras aren't exactly standardized, a palette will be needed to contain examples of colors for the other phone to be calibrated to.

QR codes have built-in redundancy. This will not. It will need to have some kind of checksum.