MobProg isclass() if-check

Usage: if (isclass(target)=<numeric class value>)

The numeric class values are:
Mage: 0
Cleric: 1
Thief: 2
Warrior: 3
Alchemist: 4
Matricist: 5
Sentinel: 6
Spare3: 7
Spare4: 8
Spare5: 9