[conformal/btcwallet] 04b51e: Add func to get next n active addresses.

[Josh Rickmar]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcwallet
  Commit: 04b51ee426909b291316825c765f3843eaa2f411
      
https://github.com/conformal/btcwallet/commit/04b51ee426909b291316825c765f3843eaa2f411
  Author: Josh Rickmar <jr...@conformal.com>
  Date:   2014-01-21 (Tue, 21 Jan 2014)

  Changed paths:
    M wallet/wallet.go
    M wallet/wallet_test.go

  Log Message:
  -----------
  Add func to get next n active addresses.

This adds a new function, ExtendActiveAddresses, to extend the number
of active addresses, generated by the address chain, by any arbitrary
positive number.  This will be used for recovering wallet addresses
from a wallet backup, as well as getting the next as many addresses as
required to keep a watching wallet in sync with an original wallet
with the private keys, or sync an original wallet with new addresses
generated by the watching wallet.