Makes the speed for an embryo to burst a config + embryo buff (#3844)

# About the pull request

Changed it from a number to a config.
Changed `larva_gestation_multiplier` to 2, as it only processes once
every 2 seconds, so it should increase the counter by 2 at a time.
Changed an `else if` to `if` as there could never be a situation where
the stage was equal to 4 but not less than 5.

# Explain why it's good for the game

Makes it easier to change, and keeps people guessing what stage they are
at when hugged.

People were operating under the assumption that it was 7.5 minutes.
However, due to `process` only running once every 2 seconds, it ended up
taking twice as long.

Stage 4 was meant to make stasis slightly less effective, but due to a
bug it just never happened.

# Changelog

:cl:
config: Moved time to burst to the config
balance: Fixed time to burst, lowering it from 15 minutes to 7.5 minutes
by default
balance: Stasis bags used on late-stage mobs properly slow growth down
less
/:cl:

code/controllers/configuration/entries/game_options.dm

@@ -122,3 +122,8 @@
 /datum/config_entry/number/extra_larva_per_burst
 	config_entry_value = 1
 	integer = FALSE
+
+/datum/config_entry/number/embryo_burst_timer
+	min_val = 1
+	config_entry_value = 450
+	integer = TRUE

code/modules/mob/living/carbon/xenomorph/Embryo.dm

@@ -38,7 +38,7 @@
 	GLOB.player_embryo_list -= src
 	. = ..()
 
-/obj/item/alien_embryo/process()
+/obj/item/alien_embryo/process(delta_time)
 	if(!affected_mob) //The mob we were gestating in is straight up gone, we shouldn't be here
 		STOP_PROCESSING(SSobj, src)
 		qdel(src)
@@ -72,24 +72,26 @@
 	if(affected_mob.in_stasis == STASIS_IN_CRYO_CELL)
 		return FALSE //If they are in cryo, the embryo won't grow.
 
-	process_growth()
+	process_growth(delta_time)
 
-/obj/item/alien_embryo/proc/process_growth()
+/obj/item/alien_embryo/proc/process_growth(delta_time)
 	var/datum/hive_status/hive = GLOB.hive_datum[hivenumber]
+	/// The total time the person is hugged divided by stages until burst
+	var/per_stage_hugged_time = CONFIG_GET(number/embryo_burst_timer) / 5
 	//Low temperature seriously hampers larva growth (as in, way below livable), so does stasis
 	if(!hive.hardcore) // Cannot progress if the hive has entered hardcore mode.
 		if(affected_mob.in_stasis || affected_mob.bodytemperature < 170)
 			if(stage < 5)
-				counter += 0.33 * hive.larva_gestation_multiplier
-			else if(stage == 4)
-				counter += 0.11 * hive.larva_gestation_multiplier
+				counter += 0.33 * hive.larva_gestation_multiplier * delta_time
+			if(stage == 4) // Stasis affects late-stage less
+				counter += 0.11 * hive.larva_gestation_multiplier * delta_time
 		else if(HAS_TRAIT(affected_mob, TRAIT_NESTED)) //Hosts who are nested in resin nests provide an ideal setting, larva grows faster
-			counter += 1.5 * hive.larva_gestation_multiplier //Currently twice as much, can be changed
+			counter += 1.5 * hive.larva_gestation_multiplier * delta_time //Currently twice as much, can be changed
 		else
 			if(stage < 5)
-				counter += 1 * hive.larva_gestation_multiplier
+				counter += 1 * hive.larva_gestation_multiplier * delta_time
 
-		if(stage < 5 && counter >= 90)
+		if(stage < 5 && counter >= per_stage_hugged_time)
 			counter = 0
 			stage++
 			if(iscarbon(affected_mob))

config/example/config.txt

@@ -239,3 +239,6 @@ GAMEMODE_ROUNDS_NEEDED 5
 
 ## Default gamemode to auto-switch back to after a round has concluded
 GAMEMODE_DEFAULT extended
+
+## How long the mob will take to chestburst, in seconds
+#EMBRYO_BURST_TIMER 450