TODO UPDATE AbstractProperties
I found this note in the documentation (during cleanup) in an article about abstract properties. I guess this is a feature request? Is it still valid? @timm
## TODO
### UPDATE AbstractProperties
Notes:
* ids are persistent. They cannot be changed.
* Maybe we should take the PropertyTypes as persistent, too or just allow a few changes: Double <-> Integer?
Roadmap:
1) Specify and implement changing the name, description and unit of AbstractProperties.
2) Specify and implement changing the reference of an abstract reference property.
3) Anything else...