Add version support and pretty-printing to mdp_decoder

[tamboril]

Modified mdp_decoder to correctly handle back-versioned streams using the recently added version support.

Added a --pretty option to mdp_decoder to use an alternate formatter for prettier output, like:

packet - timestamp: 2016-03-10 15:33:21.301819 sequence_number: 76643046 sending_time: 1454679022595400091 
    Message 1 of 2: TID 32 (MDIncrementalRefreshBook) v6
        TransactTime (60): 02/05/2016 07:30:22.595256135 (1454679022595256135)
        MatchEventIndicator (5799): LastQuoteMsg
        NoMDEntries (268): 1
        Entry 1
            MDEntryPx (270): 98890000000 (9889.0)
            MDEntrySize (271): 296
            SecurityID (48): 807004
            RptSeq (83): 14273794
            NumberOfOrders (346): 16
            MDPriceLevel (1023): 2
            MDUpdateAction (279): Change
            MDEntryType (269): Offer
    Message 2 of 2: TID 32 (MDIncrementalRefreshBook) v6
        TransactTime (60): 02/05/2016 07:30:22.595256135 (1454679022595256135)
        MatchEventIndicator (5799): LastImpliedMsg, EndOfEvent
        NoMDEntries (268): 8
        Entry 1
            MDEntryPx (270): 475000000 (47.5)
            MDEntrySize (271): 296
            SecurityID (48): 817777
            RptSeq (83): 1573080
            NumberOfOrders (346): Null
            MDPriceLevel (1023): 2
            MDUpdateAction (279): Change
            MDEntryType (269): ImpliedBid
        Entry 2...

[tfgm-bud]

Another nice addition! Thanks. -- Bud