(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/server/marketup.c

@@ -34,7 +34,6 @@
 #include "options.h"
 #include "misc.h"
 #include "player.h"
-#include "keyword.h"
 #include "empthread.h"
 #include "file.h"
 #include "server.h"