Fixing tooltip for autofill element map, which had single quotes in the
JSON examples, which of course won't work.
Fix in autofill AJAX, to unset 'usekey' input, otherwise if main form
was a usekey, the autofill lookup would apply usekey as well.
In form model _buildQuery(), changed the getMenuOrRequestVar() for
'usekey' to give preference to the QS var rather than the menu setting. 
This is necessary, for example, when using the autofill plugin, so the
plugin can unset the usekey QS, to avoid having the autofill data load
be treated as a 'usekey' lookup.  This MAY have unforeseen side effects.
Merge branch 'master' of ssh://github.com/Fabrik/fabrik