Experimental "PRAGMA query_only=BOOLEAN" statement that is able to turn
write capabilities on and off.
Fix harmless compiler warnings in the progress callback logic.
More changes to support MSVC 18.
Use the VisualStudioVersion variable instead of _MSC_VER.
More corrects to VS 2013 integration.
Environment variable names in nmake must be in all uppercase.
Add the "defer_foreign_keys" pragma and the SQLITE_DBSTATUS_DEFERRED_FKS
value for sqlite3_db_status().  This is a cherry-pick of a sequence of five
checkins in the sessions branch between [1d44e5d3c2] and [d39e65fe70].
Add the experimental "query_only" pragma.
Change the description of how sqlite3_progress_handler() works so that 
the N parameter is "approximate".  This aligns with the current implementation.
This is a documentation change only.  No changes to code.
Make sure the shell does not try to put a zero terminator on the end of an
unallocated zero-length string when running ".import" on an empty file.
Add the sqlite3_cancel_auto_extension(X) interface which will undo a prior
call to sqlite3_auto_extension(X).
Enhance the query planner so that it looks at multiple solutions to OR
expressions in the WHERE clause.
Make sure the sqlite3_prepare16 and sqlite3_prepare16_v2 interfaces do not
read past a zero-terminator if the nBytes parameter is too large.
Clear the error string pointer in sqlite3_vtab object after the error string
is transferred to SQLite.  Ticket [78588b938a11].
Enhance the sqlite3_analyzer tool to give reports on the sizes of individual
indices.
Fix copy/paste errors in comments in the transitive_closure virtual table.
No changes to code.
Documentation changes to warn that sqlite3_set_auxdata() might call the
destructor even before it returns.  Also fix the regexp extension to deal
with that case.  Ticket [406d3b2ef91c].
Fix a 8-byte alignment problem in the query planner that might cause
problems on sparc when compiled with -m32.
Ensure that all auxiliary data registered by calls to sqlite3_set_auxdata() is destroyed when the VM is halted. Partial fix for [406d3b2ef9].
Fix a typo in the previous commit.