Use the hierarchy of concepts for auto-completion of labels

[frmichel]

Use case identified in ISSA2:
In the auto-completion of labels entered by the user, it would be nice to show the sub-concepts of the concept being typed, e.g.
If I have typed "abc", I should see :

abcdef
    sub1
    sub2
        sub21
        subs22
abctsp
abcxyz

and I should be able to select anyone of those.

The idea is to show to the user not only the labels that corresponds exactly to what he has typed, but also the labels that do not match with what he has typed but that are labels of subconcepts of possible concepts.