ELECTRO-MAGNETIC ANTI-SHOPLIFTING SYSTEM FOR USE IN RETAIL STORES COMPRISING MAGNETICALLY ENCODED ADHESIVE TAGS TO BE APPLIED TO MERCHANDISE, DISPENSERS FOR APPLYING THE TAGS TO MERCHANDISE SOLD THEREWITH, AN ELECTRONIC DESENSITIZER FOR USE IN DESENSITIZING THE TAGS AND COMPUTER PANEL DETECTORS FOR PLACEMENT AT THE EXIT FROM THE STORE TO DETECT NON-DESENSITIZED TAGS LEAVING THE STORE