ENG-6419 Fixed tree structure checks so it passes on java 8
Merge pull request #1427 from VoltDB/ENG-6419

ENG-6419 Fixed tree structure checks so it passes on java 8
txnid2: do a slightly better job with the special case of mpratio=0.0 in all threads wrt suppressing mp write queries
txnid2: send output to the logger