Fix funny bug
Exactly straighten straight lines
Perpendicular endpoints
Fix sorting of endpoints per side
Use 1px black lines
Add graph controller regression tests
Refine graph controller tests
Enable relationship delete
Default to no attributes
Refactor overlays: more CSS, less state
Render chicken feet
Add ? arrowheads
Hover highlight box on arrowheads
Toggle arrowheads with click and shift-click
Move one-identifier bar a little closer