Consistency between yQ and yQS. Review arg docs.

We think that InitQuad must be called before InitQuadSens and that both
calls must use the same size nvector. See:
http://sundials.2283335.n4.nabble.com/Re-Relationship-between-CVodeQuadInit-and-CVodeQuadSensInit-td4653367.html

Minor updates to the arg documentation.