Checkpoint for dazzler integration

Got most of the block logic worked out.  There is a problem where
daligner segfaults when 'DBsplit -a' is used.  I fixed a few problems
where uninitialized variables were getting initialized elsewhere.  Don't
want to spend too many cycles figuring out to fix, so will try to work
with the 'garden path' that retains only the longest subreads.

Adapter code basically working, though somewhat slow.
Adding a new circular check recipe

Note, this does not actually circularize, rather just checks whether or
not a single sequence 'looks circular'.