Fix interactables mod issue (#298)

* Fix interactables mod issue

* Add overload back

R2API/ItemDrop/InteractableCalculator.cs

@@ -2,6 +2,7 @@
 using RoR2;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text.RegularExpressions;
 
 namespace R2API.ItemDrop {
 
@@ -13,8 +14,6 @@ This class determines which of those subset lists are present in the current run
                 and therefore which interactables should be prevented from spawning.
         */
 
-        public const int PrefixLength = 3;
-
         public readonly List<string> InvalidInteractables = new List<string>();
 
 
@@ -160,7 +159,7 @@ This is a list of interactables that require all subset lists to be populated to
             "ShrineCleanse"
         };
 
-
+        private static Regex IscRegex = new Regex("^isc");
         /*
             This function will remove isc from the interactable spawn card name, to save me typing it again everywhere.
             ie. iscShrineCleanse to ShrineCleanse
@@ -169,8 +168,8 @@ public static string GetSpawnCardName(SpawnCard givenSpawnCard) {
             return GetSpawnCardName(givenSpawnCard.name);
         }
 
-        public static string GetSpawnCardName(string givenName) {
-            return givenName.Substring(PrefixLength, givenName.Length - PrefixLength);
+        public static string GetSpawnCardName(string spawnCardName) {
+            return IscRegex.Replace(spawnCardName, "");
         }