Nightshifts & Randomized Station Time

This commit adds the Nightshift lighting mode from /tg/. From 19:00 to
07:00 in station time, the station will go into a reduced-lighting mode,
with dimmed lights across the station.

In conjunction with this, there is a new configuration option to start
the shift time at a random time other than 12:00, so that players are
more likely to experience a night shift (as opposed to having to have a
7 hour round).

code/modules/detective_work/scanner.dm

@@ -159,7 +159,7 @@
 		spawn(0)
 
 			var/found_something = 0
-			add_log("<B>[worldtime2text()][get_timestamp()] - [target_name]</B>", 0)
+			add_log("<B>[station_time_timestamp()][get_timestamp()] - [target_name]</B>", 0)
 
 			// Fingerprints
 			if(fingerprints && fingerprints.len)