Milestone report - add colored background for completed milestones

[#1]

Currently, in preview, we can see the new milestone view, with all its features. They're all good, and I like having a little control (via the new Options pulldown) over what's shown on that view.

I do wish we still could show the completed milestones with a colored background, as on the current production version. This makes it easier to quickly sort completed from incomplete. The (preview) percent complete bar is okay, but it would be preferable to have a more in-your-face indication that a milestone is complete.