Rework label value mechanism (first approach)

[s-blu]

See #154
As a first step, I want to do the following:

• Get rid of numerical label definitions
• Get rid of the label info as a note item type
• To each value input, add a "info" ckeditor input, just like before the label info was, but now right on the label value page without explicitly creating a note item
• Save these infos just like before. If there is one, render it. If there is none, prefill the ckeditor with the template
• Dont save the template if unchanged

This way I can enable multi edit on the infos and have everything right there in one place. That should be sufficient for now.