Additional transaction malleability fixes as per Bitcoin v0.9.0:
- IsStandard() transaction rules tightened to prevent relaying and mining of
  mutated transactions
- Additional information in listtransactions/gettransaction output to
  report wallet transactions that conflict with each other because
  they spend the same outputs.
- Bug fixes to the getbalance/listaccounts RPC commands, which would report
  incorrect balances for double-spent (or mutated) transactions.
- New option: -zapwallettxes to rebuild the wallet's transaction information