* src/lastlog.c: Use getrange to parse the range of users.

	* src/lastlog.c: Use getrange to parse the range of users.
	* src/lastlog.c: umin and umax do not need to be signed long. Use
	an unsigned long which might be needed to parse a GID or UID. Add
	the has_umin and has_umax to replace the -1 values.
	* src/lastlog.c: Cast dates to time_t.
	* src/lastlog.c: Prefix lastlog errors with "lastlog: ".