(weekday, daytime, daytime_range): New; replace kw_parse(). Parsing

is somewhat stricter.
(is_wday_allowed, is_daytime_allowed, is_daytime_nar,
min_to_next_daytime): New.
(demand_update_time, scheduled_update_time, next_scheduled_time,
update_time, gamehours): Use them to replace kw_parse().
(kw_parse): No longer used, remove.

src/lib/commands/upda.c

@@ -37,7 +37,6 @@
 #include "player.h"
 #include "commands.h"
 #include "optlist.h"
-#include "keyword.h"
 #include "wantupd.h"
 #include "server.h"