For the Win32 VFS, allow memory mapped files to work when compiled without WAL support.
Skip tests that require WAL mode when it is not enabled.
Enhance whereLoopCheaperProperSubset(X,Y) so that it does not report true
if X uses skip-scan less than Y, since in that case X might
deserve to be cheaper even if it is a proper subset.
Add a test case to check that the previous commit is effective.
Make sure that NULL results from OP_Column are fully and completely NULL
and do not have the MEM_Ephem bit set.  Fix for ticket [094d39a4c95ee4].
Change the query planner to do a better job of estimating the number rows
selected by a BETWEEN operator using STAT4 when both upper and lower bounds
are contained within the same sample.
Fix harmless compiler warnings in the new balance_nonroot() routine.
Fixes to the Windows VFS to allow memory mapped files to work without WAL support.