When VDBE_PROFILE is enabled, ignore negative opcode times, which sometimes
occur, perhaps due to context swaps.
Make sure ORDER BY clauses on joins that involve virtual tables and that
have a DISTINCT clause work correctly.  This is a candidate fix for
ticket [388d01d4bb8f9].  Test cases for that ticket will be checked in
separately.
Add test cases to ensure correct operation of joins with a virtual table
that include DISTINCT and ORDER BY clauses.  Verification for ticket
[388d01d4bb8f9].
Avoid transfering records between tables unless the default values for all columns are the same. Fix for [f67b41381a].
Allow the xfer optimization to proceed if the DEFAULT on the very first
column of the two tables is different.  This is a refinement of the
fix for ticket [f67b41381a].
Update requirements marks to fix typos in the requirements text.
No changes to code.
Add the sqlite3_rtree_query_callback() API to the RTree virtual table.
(Cherrypick from the sessions branch.)
Fix a test case so that it updates sqlite_stat1 consistently.
Ignore likelihood() values on indexed IPK lookups.
Merge trunk changes into this branch.
Test that the default values used when sqlite_stat1 data is not available are calculated correctly. Fixes for the same.