Concurrency fix + new scripts

Fixed some situation involving concurrency upon using getCharacters()
from MapleMap, added scripts and other bug fixes.

scripts/npc/world0/2100002.js

@@ -0,0 +1,11 @@
+var status = 0;
+
+function start() {
+    status = -1;
+    action(1, 0, 0);
+}
+
+function action(mode, type, selection) {
+    cm.openShopNPC(48);
+    cm.dispose();
+}