Updates to allow verify_ledger_json.js to calculate account_state hash
Less slicing and dicing of tag_segment/indexes
Reinstate disabled test (Thanks to encoded reminder)
Remove all traces of (now) unused tag_segment
Fix *U*Int64 parsing, add hardcore mode to ledger verifier.
Add binary <--> json encoding integration tests
* Add full json ledger dumps of ledgers 38129 and 40000 to test/fixtures
* Use `Ledger` to calculate account and transaction hashes and verify
  against dumps
Tweak to parse_options
Update SerializedObject.from_json tests
Fix merge conflicts
Merge branch 'develop' of https://github.com/ripple/ripple-lib into develop