Empty sign templates png's v3.1

added:
· small empty warning sign
· blue empty restricted area sign

added:
· "not an exit" sign
· big "notice" sign
· red "restricted area" sign
· yellow "danger" sign

other:
· edited the "Warning" sign
· changed some of the names of the png's

added:

· small empty danger sign
· mvm empty danger sign
· blu notice sign