Delete MTs and most supporting code
Remove (now unused) ScanHook from BasicDMLFunctions
Lookup directly by index ID
Varargs instead of explicit array
Minor cleanup and more QP helpers on ITBase
Re-add a cleaned up and consolidated TimePoint/TimeMarker
Builder for new concurrent, coordinated tests
Helper for defensively starting, joining test Threads
New MT for isolated DML
merge nathanlws: Start over with MT style tests

Merge pull request #1080 from nathanlws/sql-layer/remove-and-replace-mts
https://github.com/FoundationDB/sql-layer/pull/1080