Shifted more code from Reason-centric to Claim-centric.

Drawing a 'reason' now involves drawing a background, and
then separate code for drawing each 'claim'.  The support
and refute buttons are drawn relative to each claim now.

Also added a master claimList to hold unique IDs for the
individual claims (which will be needed to update events.js).
Currently support/refute button events still attach to reasons,
but they need to change claims.
Made reasonList more self-contained.

The reasonList now controls the nextReasonNumber variable.
Also fixed a small bug in hit-area of the support and refute buttons.