Updated the library.

api/src/main/java/net/jitse/npclib/internal/NPCManager.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2018 Jitse Boonstra
+ */
+
+package net.jitse.npclib.internal;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * @author Jitse Boonstra
+ */
+public final class NPCManager {
+
+    private static Set<SimpleNPC> npcs = new HashSet<>();
+
+    public static Set<SimpleNPC> getAllNPCs() {
+        return npcs;
+    }
+
+    public static void add(SimpleNPC npc) {
+        npcs.add(npc);
+    }
+
+    public static void remove(SimpleNPC npc) {
+        npcs.remove(npc);
+    }
+
+    private NPCManager() {
+        throw new SecurityException("You cannot initialize this class.");
+    }
+
+}