This adds unary plus capability. No grammar changes, per Tom's request.

src/backend/commands/command.c

src/backend/utils/adt/float.c

src/backend/utils/adt/int.c

src/backend/utils/adt/int8.c

src/backend/utils/adt/numeric.c

src/include/catalog/pg_operator.h

src/include/catalog/pg_proc.h

src/include/utils/builtins.h

src/include/utils/int8.h

src/interfaces/jdbc/org/postgresql/Connection.java