This work is to be executed on the Yii branch.

When editing subquestion or answers there should be a button 'Save as label set'.

When pressing this button the following should happen:

• A dialog JS popup with a Save and Cancel button which asks if you want to create a new label set or optionally replace an existing one. Choose between these two options by radio button. When 'New label set' is selected the user has to enter a label set name and can press save.
• If 'replace existing label set' is chosen the user can browse and choose an existing label set.
• On cancel the dialog just closes
• On save and replaceing an existing label set the old label set is removed (after additional confirmation) the new one is saved and the dialog is closed.
• On save; In general a message should appear that the label set was successfully saved.

Make sure you validate the label set name. Do not allow duplicate names. Make sure that you refresh the label set list after a new label set was added. Make sure this works for multilingual subquestions/answers and subquestions/answers having two scales.