support Threshold secondary protection

src/patchers/sierra13.a

@@ -5,7 +5,7 @@
 ; disks
 ;
 ; Cranston Manor
-; Jawbreaker ][
+; Jawbreaker
 ; Missile Defense
 ; Pegasus ][
 ; Threshold
@@ -85,6 +85,27 @@
          !byte $A0,$B9
          jmp   .exit
 
+         ;Threshold secondary protection
+
++        ldy   #11
+         jsr   SearchTrack
+         !byte $A9,$00     ;LDA #$00
+         !byte $AA         ;TAX
+         !byte $5D,$00,$96 ;EOR $9600,X
+         !byte $E8         ;INX
+         !byte $D0,$FA     ;BNE *-4
+         !byte $C9,$F3     ;CMP #$F3
+         bcs   +
+         pha
+         txa
+         adc   #$0A
+         tax
+         pla
+         ldy   #$01
+         jsr   modify
+         !byte $FC
+         jmp   .exit
+
          ;Missile Defense
 
 +        ldy   #17

src/strings/en.a

@@ -135,7 +135,7 @@ StringTable
 ; can be set directly before calling PrintByID.
 ;
 .header
-         !text "Passport by 4am               2017-12-03",$00
+         !text "Passport by 4am               2017-12-04",$00
 .mainmenu
          !text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
          !text "              "