add ability to parse fireball type using its ID

Author: Goober5000

code/fireball/fireballs.cpp

@@ -1296,7 +1296,7 @@ int fireball_get_count()
 
 void stuff_fireball_index_list(SCP_vector<int> &list, const char *name)
 {
-	stuff_int_list(list, ParseLookupType::RAW_INTEGER_TYPE);
+	stuff_int_list(list, ParseLookupType::FIREBALL_INFO_TYPE);
 
 	list.erase(std::remove_if(list.begin(), list.end(), [&](int index) {
 		if (!SCP_vector_inbounds(Fireball_info, index)) {

code/parse/parselo.cpp

@@ -3203,6 +3203,8 @@ const char* get_lookup_type_name(ParseLookupType lookup_type)
 			return "Weapon Types";
 		case ParseLookupType::WEAPON_POOL_TYPE:
 			return "Weapon Pool";
+		case ParseLookupType::FIREBALL_INFO_TYPE:
+			return "Fireball Types";
 		case ParseLookupType::MISSION_LOADOUT_SHIP_LIST:
 			return "Mission Loadout Ships";
 		case ParseLookupType::MISSION_LOADOUT_WEAPON_LIST:
@@ -3260,6 +3262,12 @@ struct StuffIntListParser
 						error_display(0, "Unable to find weapon class %s in stuff_int_list!", str.c_str());
 					break;
 
+				case ParseLookupType::FIREBALL_INFO_TYPE:
+					num = fireball_info_lookup(str.c_str());
+					if (num < 0 && warn_on_lookup_failure)
+						error_display(0, "Unable to find fireball type %s in stuff_int_list!", str.c_str());
+					break;
+
 				case ParseLookupType::RAW_INTEGER_TYPE:
 					num = atoi(str.c_str());
 					valid_negative = true;

code/parse/parselo.h

@@ -63,6 +63,7 @@ enum class ParseLookupType
 	SHIP_INFO_TYPE,
 	WEAPON_LIST_TYPE,   // to parse an int_list of weapons
 	WEAPON_POOL_TYPE,
+	FIREBALL_INFO_TYPE,
 	MISSION_LOADOUT_SHIP_LIST,
 	MISSION_LOADOUT_WEAPON_LIST,
 	CAMPAIGN_LOADOUT_SHIP_LIST,