Should show day segmentation lines on schedule bar

[mistval]

The reason I didn't do this is because days can theoretically have varying lengths depending on a user's custom temporal context script. However, that's probably a pretty niche use case, and the usability improvement from segmenting the schedule bar in terms of days seems significant.

Best of both worlds:

1. Temporal context scripts can optionally export day length info.
2. If it does so, use that information to segment the schedule bar. Otherwise, keep current behavior.