story #7510: Hide/show milestone backlog items that are done

Change-Id: I274533a0bc8ae7d8832d6ee5cfe09bd00019a334
Merge commit 'refs/changes/97/3197/9' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #7510: Hide/show milestone backlog items that are done

Change-Id: I74927767209bea346f985faebd5bd8a72927a5b9
This is Tuleap 7.6.99.53

Change-Id: Ibddc2cfa9424e25a4ad023b059b0c0f01f6f6918