Ship-type-destroyed

Ship Type Destroyed (Boolean operator)
        Becomes true when the specified percentage of ship types in this mission have been destroyed.  The ship type is a generic
type such as fighter/bomber, transport, etc.  Fighters and bombers count as the same type.

Returns a boolean value; Takes 2 arguments:
        1:      Percentage of ships that must be destroyed.
        2:      Ship type to check for.