clean up Utils.toTxReport and TxReport.resolve

simpler Utils.toTxReport, no need for so much casting and conversion
treat tempids map as opaque and use Peer.resolveTempid in TxReport.resolve
remove code duplication in DDatabase.withData
Merge pull request #6 from pellucidanalytics/topic/resolve-tempids

clean up Utils.toTxReport and TxReport.resolve