v3.1.2 - Switch only fix

[3.1.2]

Fixed

• A bus made entirely of Switch nodes rendered crushed toward the
  bottom whenever no Access Point existed anywhere on the diagram -
  the grid row reserved for a Fed Switch's own circle and connector was
  sized by whether any Access Point existed (hasAnyAp), while the
  content actually placed into that row was correctly gated by whether
  an Access Point or a Fed Switch existed (hasApRow). An
  Access-Point-free, Switch/Fed-Switch-only bus had real content
  rendered into a row deliberately sized to 0px, squashing every Fed
  Switch and the Clients box beneath it upward into an overlapping
  mess. Row height now uses the same condition that gates the content.