database improvements. record blockhash.
make var names more consistent.
fix get_tx usage.
attempt to use tx block caching again.
add traverse option to get_tx.
refactor lib/bitcoind.js.
fix parse error.
fix getTx traverse.
add get_tx_ldb.
remove get_tx_ldb.
make traverse always true for now.
no db caching for now.
remove traverse arg.
use txindex by default.
improve ismine.
disable txindex for now.
cache block by tx.