added PercentageProgressMeter for ydb progress polling callbacks #1053
added progress reporting for indexer, loader, hot optimize #1048 #1053

Also added ExceptionSaver to optimize callback.
Merge pull request #1054 from Tokutek/progress-reporting

Progress reporting for loader, indexer, hot optimize
cleaned up transaction in hot index #1035
removed read lock during build phase of hot index #1035
refs #1035 Hold the oplock around a hot index build to prevent stepdown
refs #1035 prevent multikey bit transitions during a hot index. further,
prevent reIndex. both of these may require collection close on rollback
and so cannot run while the index is still provisional.
Merge pull request #1073 from Tokutek/hot-index-locking

Hot index locking

fixes #1035
Merge branch 'bugfixes/tokumx-1.4' into releases/tokumx-1.4