Implemented new pet type (5) which summons a regular pet that locks onto

the casters target exclusively until the target dies, when target dies
the pet is killed. (Pets don't respond to commands except get lost).
This does not stack with regular pets.

Note: On live these pets cast an actual spell (Unsummon) that kills them for 20k damage,
due to how limiting that is to be hard coded, the pets will simply just
kill themselves instead.

Pending, will needd to add an optional SQL to update pet tables to convert
known live spells that use this.

zone/common.h

@@ -505,7 +505,7 @@ typedef enum {
 	petOther,
 	petCharmed,
 	petNPCFollow,
-	petHatelist			//remain active as long something is on the hatelist. Don't listen to any commands
+	petTargetLock			//remain active as long something is on the hatelist. Don't listen to any commands
 } PetType;
 
 typedef enum {