Structure
=========

Offset  Size   Type  Description
 0      4      data  protocol tag, must be 0xFB1AB1AF
 4      2      uint  sequence number
 6      2      uint  sequence ack
 8      4      data  bitfield with previous acks
12      1      uint  type code for the payload
13      3      none  padding, reserved for future use
16      0-484  data  payload, contents and length vary,
                     mostly depending on the type code

all multibyte values are in LE
the current code does no conversion, so only works on machines
with native LE (or BE if the server and all clients are on that,
but that's by accident and will break if conversion code is ever
added)


Packets
=======

Ping
----

To tell the other side we're still alive.
Both server and client will send this if they haven't sent something in
a while.

Code: 0
Payload: none
Length: 0


Login
-----

Sent from client to serveri as a request to join. The server may
respond negatively if the player name is already taken or some cap has
been reached.

Code: 1
Payload:
	0 player name, max 32 byte UTF-8 string,
	  shorter names should be zero terminated
Length: 0-32


Join
----

Sent by the server either as a response to a successful login or when
it's changing worlds.

Code: 2
Payload:
	 0 entity ID of the player, 32bit unsigned int
	 4 chunk coords of the player, 3x 32bit signed int
	16 pos/vel/rot/ang of the player, 13x 32bit float
	68 name of the world the server's currently running
	   max 32 byte UTF-8 string
Length: 68-100


Part
----

Sent by the server either as a respons to a failed login or when the
client was kicked.
Optionally sent by the client on disconnect.

Code: 3
Payload: none
Length: 0


Player Update
-------------

Sent by clients to notify the server of their changes to the player.

Code: 4
Payload:
	 0 chunk coords of the player, 3x 32bit signed int
	12 pos/vel/rot/ang of the player, 13x 32bit float
Length: 64


Spawn Entity
------------

Sent by the server to notify the client of an entity entering spawn range.

Code: 5
Payload:
	 0 entity ID, 32bit unsigned int
	 4 chunk coords of the entity, 3x 32bit signed int
	16 pos/vel/rot/ang of the entity, 13x 32bit float
	68 bounding box of the entity, 6x 32bit float
	92 flags, 32bit bitfield with boolean values
	   1: world collision
	96 entity name, max 32 byte UTF-8 string
Length: 128


Despawn Entity
--------------

Sent by the server to notify the client of an entity leaving spawn range.

Code: 6
Payload:
	0 entity ID, 32bit unsigned int
Length: 4


Entity Update
-------------

Sent by the server to notify the client of updated entity properties.
Contained entities must be ordered by ascending entity ID.

Code: 7
Payload:
	 0 number of entities, 32bit int, 1-7
	 4 chunk coords of the entity, 3x 32bit signed int
	16 pos/vel/rot/ang of the entity, 13x 32bit float
	68 next entity...
Length: 4 + multiple of 64, max 452