Standard binary serialization/deserialization is mostly used in VM to put/get
elements into/from storage, so they never should exceed MaxSize (otherwise one
won't be able to deserialize these items).
This patch leaves EncodeBinaryStackItem unprotected, but that's a streaming
interface, so it's up to the user of it to ensure its appropriate use (and our
uses are mostly for native contract's data, so they're fine).
