bump version
Fix Litecoin proof_of_work_limit and block reward halving
Add Dogecoin network parameter support
remove freicoin network parameters
add dogecoin helper method

  Bitcoin.dogecoin? == true if network project is set to dogecoin
Add new testnet3 seeds
Fix exception when parsing from headers only

  I was getting an argument exception because Block.new was expecting an argument: https://github.com/lian/bitcoin-ruby/blob/master/lib/bitcoin/protocol/parser.rb#L63

  This fixes the problem, but I think the API would be a bit cleaner if we could do Block.new(data, header_only: true)
Added Tx#from_toshi_hash methods to deal with new toshi hash keys
combine Tx#from_hash and Tx#from_toshi_hash
Add docs badge to README

[ci skip]
clean up network descriptions
Added chain ID for Namecoin.

AuxPoW support now depends on presence of an AuxPoW chain ID, rather than being Namecoin-specific. This enables support for Dogecoin AuxPoW.
clean up address and script types

this makes for consistent naming of the address/script types everywhere,
gives us some more flexibility to introduce new types,
makes #encode/decode_address more generic and
highlights the importance of carrying the address type along the hash160,
while still preserving the old APIs for compatibility

only change is the return value of Script#type
fix block builder target comparison
fix regtest proof_of_work_limit
tx builder: option to add extra fee on top of the calculated minimum fee
key regenerates pubkey after setting privkey
minor fix in CommandClient
Script #get_keys_provided for multisig scripts
script: leave nil object when address cannot be decoded from pubkey