Label Consistency Handling

[pLeminoq]

There are some issues with the consistency handling of labels since the label type has been introduced:

• It seems that for devices with multiple units the LabelType will be directly converted to a string for its DAL units. E.g. a button received the label "entry { key: "en" value: "Gira Gira_5142 Device-3"}_Gira_429496730250000_BUTTON_1" for me.
• The warning message printed by the label consistency handler for dal units also prints the label type as a string.
• A consistency handler should be added that verifies the language codes in the label type.