Show that puzzle/meta is solved in breadcrumbs

[Torgen]

Relates to #260 especially. If you were in a puzzle, then went up the trail to the meta, the icon should be an extra visual indication that the puzzle has been solved.

[Torgen]

With the checkmark available in bootstrap, it can look something like this:

I could replace the icon with the check or turn the icon green instead.
Another option: use borders to circle the icon: