Modify listtransactions to more closely match the Bitcoin Core API.
Modify listtransactions to more closely match the Bitcoin Core API.

This change modifies the output of the listtransactions JSON-RPC by:

1. Removing "sends" for transactions that have a spent output
2. Reporting all "receives" of a tx before any "sends"
3. Sorting results from oldest to newest

Together, these changes make the JSON objects in the result match the
order and amounts of the listtransactions call in Bitcoin Core.

jrick/dcrwallet,jrick/btcwallet,jrick/dcrwallet,decred/dcrwallet,decred/dcrwallet,jrick/btcwallet