Enhance the logest.c utility with new operators: "dup", "inv", "log", and
"nlogn".  Provide help on an invalid input.
Minor cleanup of the code in the query planner that computes the costs 
estimates for the various plans.  There are no changes to the costs at this
time.  But the code is slightly more readable now and that might facilitate
future enhancements.
Enhance the sqlite3VdbeRecordCompare() routines so that if they encounter
database corruption, they will set the UnpackedRecord.isCorrupt field and
return 0.  The sqlite3BtreeMovetoUnpacked() routine detects this and returns
SQLITE_CORRUPT, causing the corruption to be reported back to the top-level.
Fix a harmless compiler warning.
Disable the wal64k.test script for non-unix systems since it depends on
unix-only features.
Avoid a (harmless) buffer overread that is possible on an OOM when
MEMSYS5 is engaged.
In the command-line shell, run set writable_schema before running the
".clone" command.
Fix a typo in the "Synopsis:" comment for the OP_VFilter opcode.
Use OP_Copy instead of OP_SCopy when moving results out of a subquery,
to prevent the subquery results from changing out from under the outer
query.  Fix for ticket [1e64dd782a126f48d78].
Merge all recent changes from trunk,
including the fix for the OP_SCopy-vs-OP_Copy problem.