add support for modified BB encryption

src/PSOEncryption.hh

@@ -65,8 +65,11 @@ protected:
 class PSOBBEncryption : public PSOEncryption {
 public:
   struct KeyFile {
-    uint32_t initial_keys[18];
-    uint32_t private_keys[1024];
+    // initial_keys are actually a stream of uint32_ts, but we treat them as
+    // bytes for code simplicity
+    uint8_t initial_keys[0x12 * 4];
+    uint32_t private_keys[0x400];
+    uint8_t is_modcrypt;
   } __attribute__((packed));
 
   PSOBBEncryption(const KeyFile& key, const void* seed, size_t seed_size);