Renames delta time to be a more obvious name (#74654)

This tracks the seconds per tick of a subsystem, however note that it is
not completely accurate, as subsystems can be delayed, however it's
useful to have this number as a multiplier or ratio, so that if in
future someone changes the subsystem wait time code correctly adjusts
how fast it applies effects

regexes used

git grep --files-with-matches --name-only 'DT_PROB' | xargs -l sed -i
's/DT_PROB/SPT_PROB/g'
git grep --files-with-matches --name-only 'delta_time' | xargs -l sed -i
's/delta_time/seconds_per_tick/g'

code/controllers/subsystem/processing/processing.dm

@@ -36,15 +36,15 @@ SUBSYSTEM_DEF(processing)
  * This proc is called on a datum on every "cycle" if it is being processed by a subsystem. The time between each cycle is determined by the subsystem's "wait" setting.
  * You can start and stop processing a datum using the START_PROCESSING and STOP_PROCESSING defines.
  *
- * Since the wait setting of a subsystem can be changed at any time, it is important that any rate-of-change that you implement in this proc is multiplied by the delta_time that is sent as a parameter,
- * Additionally, any "prob" you use in this proc should instead use the DT_PROB define to make sure that the final probability per second stays the same even if the subsystem's wait is altered.
+ * Since the wait setting of a subsystem can be changed at any time, it is important that any rate-of-change that you implement in this proc is multiplied by the seconds_per_tick that is sent as a parameter,
+ * Additionally, any "prob" you use in this proc should instead use the SPT_PROB define to make sure that the final probability per second stays the same even if the subsystem's wait is altered.
  * Examples where this must be considered:
- * - Implementing a cooldown timer, use `mytimer -= delta_time`, not `mytimer -= 1`. This way, `mytimer` will always have the unit of seconds
- * - Damaging a mob, do `L.adjustFireLoss(20 * delta_time)`, not `L.adjustFireLoss(20)`. This way, the damage per second stays constant even if the wait of the subsystem is changed
- * - Probability of something happening, do `if(DT_PROB(25, delta_time))`, not `if(prob(25))`. This way, if the subsystem wait is e.g. lowered, there won't be a higher chance of this event happening per second
+ * - Implementing a cooldown timer, use `mytimer -= seconds_per_tick`, not `mytimer -= 1`. This way, `mytimer` will always have the unit of seconds
+ * - Damaging a mob, do `L.adjustFireLoss(20 * seconds_per_tick)`, not `L.adjustFireLoss(20)`. This way, the damage per second stays constant even if the wait of the subsystem is changed
+ * - Probability of something happening, do `if(SPT_PROB(25, seconds_per_tick))`, not `if(prob(25))`. This way, if the subsystem wait is e.g. lowered, there won't be a higher chance of this event happening per second
  *
  * If you override this do not call parent, as it will return PROCESS_KILL. This is done to prevent objects that dont override process() from staying in the processing list
  */
-/datum/proc/process(delta_time)
+/datum/proc/process(seconds_per_tick)
 	set waitfor = FALSE
 	return PROCESS_KILL

code/controllers/subsystem/processing/reagents.dm

@@ -4,7 +4,7 @@ PROCESSING_SUBSYSTEM_DEF(reagents)
 	name = "Reagents"
 	init_order = INIT_ORDER_REAGENTS
 	priority = FIRE_PRIORITY_REAGENTS
-	wait = 0.25 SECONDS //You might think that rate_up_lim has to be set to half, but since everything is normalised around delta_time, it automatically adjusts it to be per second. Magic!
+	wait = 0.25 SECONDS //You might think that rate_up_lim has to be set to half, but since everything is normalised around seconds_per_tick, it automatically adjusts it to be per second. Magic!
 	flags = SS_KEEP_TIMING
 	runlevels = RUNLEVEL_GAME | RUNLEVEL_POSTGAME
 	///What time was it when we last ticked