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
Unrelated, add alternative to MoreExecutors.sameThreadExcutor which allocates a new executor that does locking itnernally
For ENG-6115, clean up various stream snapshot error messages
Unrelated, add missing always pretouch flag to default case
For ENG-6226, remove stack trace to console on cancelled key exception
Don't log in community that we can't load a pro class like SnapshotIOAgentImpl
For ENG-6227, don't log a scary warning a snapshots collide
Unrelated, use CoreUtils.SAMETHREADEXECUTOR instead of MoreExecutors.SameThreadExecutor because it doesn't do any allocations and synchronization
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
For ENG-6115, cleanup based on Stefano's feedback
Merge branch 'master' into pve-clean