Updated PocketMine-NBT dependency with string corruption fix

This fix doesn't fix existing data, but it will prevent the bug happening in the future by capping the length of strings to 32767 bytes, and throwing an exception if too long.

composer.json

@@ -24,7 +24,7 @@
       "pocketmine/raklib": "dev-master#9b50878021ca545684fc1fd2d9333911ab2988e1",
       "pocketmine/pocketmine-spl": "^0.2.0",
       "pocketmine/pocketmine-binaryutils": "dev-master#a7cd5303a3b215d26bf9be76682ce9311f40e887",
-      "pocketmine/pocketmine-nbt": "dev-master#9bd51874c315fd7f3ebf81e3c09f1993ea9b7954"
+      "pocketmine/pocketmine-nbt": "dev-master#3bb6fb1b1b7b3aa40939764a5479b2758f3c135e"
    },
    "autoload": {
       "psr-0": {

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "a293be03d455a19167a576d4980c3e04",
+    "content-hash": "08158e4b18863a13bde2505e4b274f0c",
     "packages": [
         {
             "name": "pocketmine/pocketmine-binaryutils",
@@ -45,12 +45,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/pmmp/PocketMine-NBT.git",
-                "reference": "9bd51874c315fd7f3ebf81e3c09f1993ea9b7954"
+                "reference": "3bb6fb1b1b7b3aa40939764a5479b2758f3c135e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/pmmp/PocketMine-NBT/zipball/9bd51874c315fd7f3ebf81e3c09f1993ea9b7954",
-                "reference": "9bd51874c315fd7f3ebf81e3c09f1993ea9b7954",
+                "url": "https://api.github.com/repos/pmmp/PocketMine-NBT/zipball/3bb6fb1b1b7b3aa40939764a5479b2758f3c135e",
+                "reference": "3bb6fb1b1b7b3aa40939764a5479b2758f3c135e",
                 "shasum": ""
             },
             "require": {
@@ -71,7 +71,7 @@
                 "source": "https://github.com/pmmp/PocketMine-NBT/tree/master",
                 "issues": "https://github.com/pmmp/PocketMine-NBT/issues"
             },
-            "time": "2018-02-07T19:47:07+00:00"
+            "time": "2018-02-11T15:53:29+00:00"
         },
         {
             "name": "pocketmine/pocketmine-spl",