Only chain rows should force their nearest connector gutter back to vertical.
Inherited gutters from older last-sibling ancestors must stay suppressed so
linear continuations under nested branched grandchildren do not draw floating
vertical lines below unrelated branch connectors.
Updated the TUI renderer, mirrored the HTML export renderer, regenerated the
HTML template, and extended the #2298 regression to cover nested branched
grandchildren with linear continuations.
Fixes#2298
roboomp
5e6f5bf66d