Set max Zeny to 2,147,483,647 (#2756)

* This is the client's limitation.

src/common/mmo.h

@@ -47,7 +47,7 @@
 * Note: The client seems unable to receive data for more than 4 slots due to all related packets having a fixed size. */
 #define MAX_SLOTS 4
 #define MAX_AMOUNT 30000 ////Max amount of a single stacked item
-#define MAX_ZENY 1000000000 ///Max zeny
+#define MAX_ZENY INT_MAX ///Max zeny
 #define MAX_BANK_ZENY SINT32_MAX ///Max zeny in Bank
 #define MAX_FAME 1000000000 ///Max fame points
 #define MAX_CART 100 ///Maximum item in cart