Replace all mentions of VECTORs in the reference for MAPs
Created by: Lartu
LDPL VECTORs have been formally renamed to LDPL MAPs. The old keyword can still be used but the correct way of declaring VECTORs is now to write MAP instead. This should be reflected in the documentation, and every mention of an VECTOR should be changed to MAP. One should mention also that MAPs were formally called VECTORs and that the keyword is still supported albeit deprecated.