Add filter for "Unmaintained" software

[mjl-]

The list is getting wide. Showing only maintained software by default makes it more usable. Toggling the "Unmaintained" checkbox would show all software including unmaintained.

[marclaporte]

@mjl-

Makes sense. However, what guidelines would you have in mind for maintained vs unmaintained? Would there also be something in the middle? (ex.: minimally maintained or security fixes only)

[mjl-]

I had added the checkbox "Maintained" some time ago. But it didn't really help that much. Most of the items appear to be maintained. The tooltip for the checkbox says "Releases or changes have been made recently. For example in the past 2 years.". I wanted to leave it a bit fuzzy. When software stops being maintained, it often fizzles out, and there's no clear moment where it goes from maintained to unmaintained. So probably best left up to interpretation. (:
In my mind, software that releases security fixes is software that is being maintained.