Use only a single OP_MakeRecord instead of two when constructing entries
to go onto a sorter.
merge fixes from trunk
Further enhancements to geneverated VDBE code for ORDER BY.
Remove a pointless OP_Once operation in ORDER BY clauses with LIMIT.
Remove an unnecessary temporary register allocation.
Avoid unnecessary moving of content between registers during an ORDER BY.
Omit the sequence value from sorter records used by GROUP BY queries that cannot use an index.
Remove the sequence values from sorter records used by ORDER BY as well.
Fix a problem in the code added by [707ea170b3] causing vdbesort.c to sort unstably.
Merge enhancements and fixes from trunk.
Merge the latest trunk changes and the fix for the crash on a corrupt
database.
Enhance the logest.c utility with new operators: "dup", "inv", "log", and
"nlogn".  Provide help on an invalid input.
Use xFetch() to access temporary files in vdbesort.c. Use a single large allocation instead of many small allocations when accumulating records in vdbesort.c. This is an interim commit - it allocates a buffer the size of the page-cache every time data is sorted.
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.
Instead of allocating a single large buffer at the beginning of each sort operation, start with a small buffer and extend it using realloc() as required.
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.
Merge the latest changes from trunk.
Merge latest changes from orderby-planning branch.