Log plugin

The log plugin writes all messages to the console in human-readable form:

$ python -m mc3p.proxy --plugin mc3p.plugin.log angband

Client -> Server 0x02 (Handshake) 65 bytes
    username: u'GhostOfGalt;192.168.1.131:34343'
    raw_bytes: ... 
    msgtype: 2

Server -> Client 0x02 (Handshake) 37 bytes        msgtype: 2
    raw_bytes: ... 
    hash: u'-52c84c10a10525f7'

Client -> Server 0x01 (None) 42 bytes
    username: u'GhostOfGalt'
    nu8: 0        nu6: 0
    nu7: u''         nu4: 0
    nu5: 0        nu2: 0
    raw_bytes: ...         msgtype: 1
    proto_version: 29
Server -> Client 0x01 (Login packet) 34 bytes
    reserved: u''         world_height: 0
    difficulty: 1        raw_bytes: ... 
    msgtype: 1        server_mode: 0
    max_players: 20        level_type: u'default'
    dimension: 0        eid: 49554
Server -> Client 0x06 (Spawn position) 13 bytes
    y: 50
    x: 0        z: 0
    msgtype: 6        raw_bytes: ... 
Server -> Client 0xca (Abilities) 5 bytes
    instant_destroy: False        msgtype: 202 
    allow_flying: False        invulnerable: False
    flying: False        raw_bytes: ...