shield types

BUR #3 has been approved by @VeliteAquila.

create implication aspis -> shield
create implication pelta -> shield
create implication parma -> shield
create implication thureos -> shield
create implication diplyon -> shield
create implication scutum -> shield

implying multiple shield types

The bulk update request #3 (forum #5) has been approved by @VeliteAquila.