Label not linked to field should not be italic

As they are not linked to a field, there is nothing to edit.
Also tryton does not put italic style because of missing pango.AttrStyle but we could use CSS for that.

assigned to @ced

added sao tryton type::behavior + 1 deleted label

added 1 deleted label and removed 1 deleted label

review58381002 updated at https://codereview.tryton.org/58381002/#ps1

review58381002 updated at https://codereview.tryton.org/58381002/#ps20001

review58381002 updated at https://codereview.tryton.org/58381002/#ps40001

New changeset 7a96730277f0 by Cédric Krier in branch 'default':
Do not set editable class to label not linked to field
https://hg.tryton.org/sao/rev/7a96730277f0

added 1 deleted label and removed 1 deleted label

closed

New changeset e6ae7b52038b by Cédric Krier in branch 'default':
Use apply_label_attributes instead of get_label_attributes
https://hg.tryton.org/tryton/rev/e6ae7b52038b

New changeset 6f7e021a4830 by Cédric Krier in branch 'default':
Use the same code to set style on label
https://hg.tryton.org/tryton-env/rev/6f7e021a4830