Query planner heuristic update:
When doing a full table scan on a table that has an equality constraint on
an unindexed column, do not allow the estimated number of output rows to
be greater than half the total number of rows in the table.
Fix a couple of typos in comments.  No changes to code.
Add the sqlite3_memdebug_title_count global variable, used during debugging
to count the number of invocations of test_memdebug_settitle.  By examining
this variable in the debugger after a segfault, one can then set a breakpoint
on test_memdebug_settitle that will fire just before the problem.
Do not require a page-size change if the attempt to change the page size
failed due to an OOM error.