Add option for max length prefix size

[Minikloon]

MCPE packet 0x38 originating from the client sets a Minecraft block metadata by sending its nbt.

Clients may fool servers and cause performance issues by spamming max size length prefixes in that nbt. fNbt will allocate these massive arrays and this may cause OutOfMemoryExceptions.

Affected tags:

• Byte array
• String
• List
• Int array

I suggest adding a MaxBufferSize property to NbtBinaryReader with a convenience proxy in NbtFile.

[mstefarov]

Hmm this is an interesting problem that I have not considered. Thanks for bringing it up. I will prioritize this for the next release.