[frjninai] QR code copy machine

Create a copy machine that, when it copies a page with a QR code on it, does error correction to restore the code to pristine form, with any errors corrected.

Copies of copies don't get worse.  It's weird how a copy could be better than the original.

(It will unfortunately undo any artistic modifications that graphic designers sometimes do to QR codes.)

Relatedly, create a scanner that identifies errors in a QR code, perhaps for a situation in which manual corrections are possible.