Small erismed fix (#8548)

* fixed excessive rounding in determining wounding
fixed external damage overflow in determining internal dam
fixed immoderate division in determining dam

* tumors now have appropriate children

code/modules/organs/external/damage.dm

@@ -28,9 +28,9 @@
 		var/transferred_damage_amount
 		switch(damage_type)
 			if(BRUTE)
-				transferred_damage_amount = amount - (max_damage - brute_dam) / armor_divisor / 2
+				transferred_damage_amount = amount - (max(max_damage - brute_dam, 0) / (1 + ((armor_divisor-1) / 2)))
 			if(BURN)
-				transferred_damage_amount = amount - (max_damage - burn_dam) / armor_divisor / 2
+				transferred_damage_amount = amount - max(max_damage - burn_dam, 0) / (armor_divisor > 1 ? 1 + abs(armor_divisor-1) / 2: 1 - abs(armor_divisor-1) / 2)
 			if(HALLOSS)
 				transferred_damage_amount = 0
 			else

code/modules/organs/internal/_internal.dm

@@ -125,7 +125,7 @@
 	if(!damage_type || status & ORGAN_DEAD)
 		return FALSE
 
-	var/wound_count = max(0, round(amount / (damage_type == BRUTE || damage_type == BURN ? 4 : 8)))	// At base values, every 8 points of damage is 1 wound, or 4 if brute or burn.
+	var/wound_count = max(0, ROUND_PROB(amount / (damage_type == BRUTE || damage_type == BURN ? 4 : 8)))	// At base values, every 8 points of damage is 1 wound, or 4 if brute or burn.
 
 	if(!wound_count)
 		return FALSE

code/modules/organs/internal/internal_wounds/organic.dm

@@ -258,14 +258,14 @@
 	severity_max = 1
 	organ_efficiency_multiplier = -0.10
 
-/datum/component/internal_wound/organic/debuff_tumor
+/datum/component/internal_wound/organic/debuff_tumor/default
 	name = "tumor"
 
-/datum/component/internal_wound/organic/debuff_tumor_15
+/datum/component/internal_wound/organic/debuff_tumor/t15
 	name = "tumor"
 	organ_efficiency_multiplier = -0.15
 
-/datum/component/internal_wound/organic/debuff_tumor_5
+/datum/component/internal_wound/organic/debuff_tumor/t5
 	name = "tumor"
 	organ_efficiency_multiplier = -0.05