btcd v0.5.0-alpha

• Optimize initial block download by introducing a new mode which
  downloads the block headers first (up to the final checkpoint)
• Improve peer handling to remove the potential for slow peers to cause
  sluggishness amongst all peers
  (#63)
• Fix an issue where the initial block sync could stall when the sync peer
  disconnects (#62)
• Correct an issue where --externalip was doing a DNS lookup on the full
  host:port instead of just the host portion
  (#38)
• Fix an issue which could lead to a panic on chain switches
  (#70)
• Improve btcctl utility in the following ways:
  • Show getdifficulty output as floating point to 6 digits of precision
  • Show all JSON object replies formatted as standard JSON
  • Allow btcctl getblock to accept optional params
  • Add getaccount command (wallet-specific)
  • Add getaccountaddress command (wallet-specific)
  • Add sendrawtransaction command
• Continue cleanup and work on implementing RPC API calls
  • Update getrawmempool to support new optional verbose flag
  • Update getrawtransaction to match the reference client
  • Update getblock to support new optional verbose flag
  • Update raw transactions to fully match the reference client including
    support for all transaction types and address types
  • Correct getrawmempool fee field to return BTC instead of Satoshi
  • Correct getpeerinfo service flag to return 8 digit string so it
    matches the reference client
  • Correct verifychain to return a boolean
  • Implement decoderawtransaction command
  • Implement createrawtransaction command
  • Implement decodescript command
  • Implement gethashespersec command
  • Allow RPC handler overrides when invoked via a websocket versus
    legacy connection
• Add new DNS seed for peer discovery
• Display user agent on new valid peer log message
  (#64)
• Notify wallet when new transactions that pay to registered addresses
  show up in the mempool before being mined into a block
• Support a tor-specific proxy in addition to a normal proxy
  (#47)
• Remove deprecated sqlite3 imports from utilities
• Remove leftover profile write from addblock utility
• Quite a bit of code cleanup and refactoring to improve maintainability