R1:300910f462a3

Allow columns to have a point limit

Summary:
Fixes T5885. This implements optional soft point limits for workboard columns, per traditional Kanban.

- Allow columns to have a point limit set.
- When a column has a point limit, show it in the header.
- If a column has too many points in it, show the column and point count in red.

@chad, this could probably use some design tweaks. In particular:

- I changed the color of "hidden" columns to avoid confusion with "overfull" columns. We might be able…