Add log messages and debug checks to COW context.
Fix mac compilation errors.
Don't check COW remaining count if the table is empty.
Merge branch 'master' of https://github.com/alexeevm/voltdb
resolved merge conflict
Initialize PVE in constructor from the global params from VoltDBEngine
Merge branch 'ENG-451-pve' of https://github.com/alexeevm/voltdb into ENG-451-pve

Conflicts:
	src/ee/expressions/stringfunctions.h
ENG-6404 Changed @Statistics to correctly display weighted percentages
Merge branch 'master' of github.com:VoltDB/voltdb into ENG-6404
ENG-6404 Added a rounding test and fixed test results to reflect rounding changes
Merge branch 'master' into ENG-451-pve
Merge branch 'master' into pve-clean
Revert COW changes that got incorrectly merged in at some point.
Merge pull request #1409 from VoltDB/pve-clean

Pve clean
Merge pull request #1403 from VoltDB/ENG-6404

ENG-6404 Changed @Statistics to correctly display weighted percentages