Hillclimbing storyline layout.
Made entity line titles translucent except on mouseover.
Deterministic hillclimbing.
Entity line labels don't do mouseover but let focus pass to elements underneath.
Individual entity line point y positions.
Entity lines change rows only just before next node.

This should prevent most overlaps with nodes that aren't on the line.
Draw entity lines with d3 diagonals instead of lines.
Cleanup.
Diagonal entity lines don't move until before next node.
More cleanup.
Flexible node heights.
More improvements to entity line drawing.
Fix to entity line y positions.
More cleanup.