Add handing for Row#toString for fields with null types.
Update the pipeline-select Server Files test to include the problem
query from the YamlITs for testing purposes.
Address three found bugs with the lookahead processing not managing the
cursor state properly. 

Intersect_Ordered#nextBindings() needed to be smarter about handling the
underlying bindings as the lookahead may have moved the input binding
forward by several leaps depending upon lookahead. 

Intersect_Ordered#cancelBindings() needed to mark the cursor as closed
to force the parent operator to re-open it, so it would correctly reset
the two input operators. 

Map_NestedLoops - Two places to check if the input cursor is open
already, and if not make sure it is before reading from it. 

Also, update some of the debug messages to make it clearer where (and
why) the debug messages are appearing. Do the same for several asserts
as well.
Add second test for pipeline select
Merge remote-tracking branch 'github/master' into fix-assert-insersect-ordered
Merge remote-tracking branch 'github/master' into fix-assert-insersect-ordered
Update new test to functional, passing tests.
Remove the previously inserted assert as too much.
Alter the debug message which was causing tests to fail.
Add debug logging under LOG_EXECUTION
i before e, except after c, or when sounding like a as in neighbor or
weigh.
Merge remote-tracking branch 'github/master' into fix-assert-insersect-ordered
Per discussion with Mike, update the
MultipleQueryBindingsCursor#cancelBindings() to cancel both the primary
cursor as well as the input cursors to keep the bindings in synch with
child cursor bindings.
merge tjoneslo: Fix assert intersect ordered

Merge pull request #1424 from tjoneslo/sql-layer/fix-assert-insersect-ordered
https://github.com/FoundationDB/sql-layer/pull/1424