It was still possible to hit the lua instruction limit on larger prints, so I've scaled back the number of operations per loop to (hopefully) fix it

Cleaned up the regex filter for "number of printers" textbox on the console
Clicking the plus button on the console when there's no number entered now sets the number of printers to 1
Printers will now abort and show "Protected" error if any of the print area has tile protection
Scanners will now ignore areas with tile protection when clearing the area after a scan

Fix for scanners crashing when wired to objects that weren't scanning markers