** Commands:

* All messages should be in ASCII-text format (easy to debug), exept cases noted explicitly.
* No answer in some period of time means error. We should add some error handlers here.

* Login
* Ping
* Get maps
* Choose map/connect to game
* Move/Update

Every command should be packed as following:

----------------------------------------------------
|Header:4b|PacketSize:2b|Packet:PacketSize|CRC32:4b|
----------------------------------------------------

Header == "HOMM" (4bytes)
CRC32 must be computed against Header, PacketSize and Packet.

** Login:

Q: <<"L=":2b, PlayerName:VariableSize>>
A: <<"L=OK":4b, "ID=":4b, PlayerID:16b>>
A: <<"L=FAIL":6b, "REASON=":7b, ErrorReason:?b>>

Notes:

* PlayerName - some textual name ("Crag Hack", "Conan The Destroyer", "Jaunty Jackalope")
* PlayerID - some text, probably hexnumber (0x123, 0xDEADBEEF, 123456@127.0.0.1)
* ErrorReason - some number (0x00001, 12345, 0543). Maybe better to use some text messages?

** Ping

Q: <<"Ping":4b, PlayerID:16b>>
A: <<"Pong":4b>>
A: <<"NOTFOUND":8b>>

Notes:

* If ping from server to (probably NAT'ed) client, then client must check PlayerId against its own.
  Client may reply with "NOTFOUND"
* If ping from client to server, then server should update address of PlayerID (if found) or
  reply with "NOTFOUND" otherwise.
* Server must ping all clients periodically

** Get maps

Q: <<"Maps":4b, "F=":2b, FromNumber:2b, "T=":2b, ToNumber:2b>>
A: <<"Map":3b, "N=":2b, MapNumber:2b, "F=":2b, TotalMapsNumber:2b>> ++ <<here we dump map info (name, size, diffuculty, already connected users, map data, etc>>
A: <<"Map":3b, "N=":2b, MapNumber:2b, "NOTFOUND":8b>>

Notes:

* Firstly, user should query maps from 0 to 0, and server starts sending all maps
* User also may request maps starting from 0 to 1, and from 1 to 2, and so on, to create list of maps one by one.
* NOTFOUND means end of maps list.

** Choose map/Connect to map

Q: <<"Game":4b, MapNumber:2b, PlayerID:16b, PlayAs:2b>>
A: <<"Game":4b, MapNumber:2b, PlayerID:16b, PlayAs:2b, "OK":2b, GameID:16b>>
A: <<"Game":4b, MapNumber:2b, PlayerID:16b, PlayAs:2b, "ERR":3b>>

** Move/Update

Q: <<"UPDATE":6b, "GameID=":7b, GameID:16b, "Player=":7b, PlayerID:16b, "Object=":7b, ObjectID:16b, UpdateID:16b>> ++ <<here we dump information about changes in object's state>>
A: <<"UPDATE":6b, "GameID=":7b, GameID:16b, "Player=":7b, PlayerID:16b, "Object=":7b, ObjectID:16b, UpdateID:16b, "OK":2b>>
A: <<"UPDATE":6b, "GameID=":7b, GameID:16b, "Player=":7b, PlayerID:16b, "Object=":7b, ObjectID:16b, UpdateID:16b, "ERR":3b>>

Notes:

* All updates should pass through server (it validates them and rejects cheats and malformed updates)
* We should add game monster's updates as well
* Each update must be immediately sent to all connected clients (probably to initial sender too)
* Server can generate updates too
* Every update which sends/retransmits from Server to clients must have correct Player field and value