2.0.1-747-g73dc244b8

Assign artifact IDs for generated randarts

May resolve https://github.com/NickMcConnell/FAangband/issues/435 (previous behavior had all the randarts with an ID of zero at the exit of initialize_random_artifacts() so marking one created would mark all as created).  Also reduce the number of reallocations in initialize_random_artifacts() to be more efficient.