Emit metaDataChanged when changing properties
Emit metaDataChanged when changing properties

Properties is a dictionary inside the metadata dictionary. If you change one of the properties, it'll check afterwards if the dictionary is different from what it was before, but since the dictionary is passed by reference all the time, it'll think that the dictionary didn't change: The reference is still the same, so the thing it checks against is updated along.
This solution is a bit ugly but it does notice when the metadata changed inside the properties and then emits a change signal.

Contributes to issue CURA-2822.

fieldOfView/Cura,Curahelper/Cura,ynotstartups/Wanhao,fieldOfView/Cura,ynotstartups/Wanhao,Curahelper/Cura