Reorganize fb-survey signals slightly
Reorganize fb-survey signals slightly

1. Break up the behavior section into subsections so the table isn't so
intimidatingly large.

2. Place current signals above discontinued counterparts when possible.

cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata