Add batch features
 - Multiple passphrases as arguments or from file (-f)
 - Filter by min/max passphrase length (--min-length, max-length)
 - Filter by candidate bitcoin addresses file (-c/--candidates-file)
 - Expand provided passphrases by cartesian product/permutation/combination
   (--expander, -n)
 - NB Output now in the format "<passphrase> <address> <private key>
Merge pull request #1 from moreati/master

Batch mode enhancements