Element confidence filter

Requires !1685 (merged), closes #1016 (closed)

requested review from @babadie

assigned to @erwanrouchet

mentioned in merge request frontend!1266 (merged)

added 4 commits

• 27c96335...e6d5b09d - 3 commits from branch master
• 86d21879 - Filter elements by confidence

Compare with previous version

mentioned in commit 95eb85e0

merged