The settingslist() code only replicated showvisitorprofile(), so remove
founctions and point Twig_Function_Method() to showvisitorprofile
Add $visitor_id to update() function paramters.  Function doesn't seem
to be called presently, but it is one less "red flag"
Replace fetachAll()/array_shift() with fetchAssoc().

c.f.
http://doctrine-dbal.readthedocs.org/en/latest/reference/data-retrieval-and-manipulation.html#fetchassoc
Remove some redundancy and add comments to checkvisitor() and
showvisitorprofile()