Aggregations are not shown in navigator if created or updated

Please try:

1. create an aggregation
2. create an item
3. put the item in the aggregation
4. look at navigator/tgsearch
5. --> no item in navigator, but in project's root folder

...or see project in textgridlab.org: bug#collections (TGPR-2a4c2bef-c22a-dd9e-4129-665dddaf6c27)