support newer message format with lz4 compression

[SingingBush]

I've been taking a look at the source in consumer.d within processBuffer. It seems kafka-d only handles the older message format (prior to Kafka 0.11) which are structured like:

MessageSet (Version: 0) => [offset message_size message]
offset => INT64
message_size => INT32
message => crc magic_byte attributes key value
    crc => INT32
    magic_byte => INT8
    attributes => INT8
        bit 0~2:
            0: no compression
            1: gzip
            2: snappy
        bit 3~7: unused
    key => BYTES
    value => BYTES

newer versions of Kafka use the following structure which includes a timestamp as well as also supporting lz4 compression.

MessageSet (Version: 1) => [offset message_size message]
offset => INT64
message_size => INT32
message => crc magic_byte attributes timestamp key value
    crc => INT32
    magic_byte => INT8
    attributes => INT8
        bit 0~2:
            0: no compression
            1: gzip
            2: snappy
            3: lz4
        bit 3: timestampType
            0: create time
            1: log append time
        bit 4~7: unused
    timestamp => INT64
    key => BYTES
    value => BYTES