* Add unit system to Project Information and store with document.
* Remove the project unit system
* Restore correct document activation signalling to fix test fail
* Remove commented out dead lines
* Restore ignore option for project unit schemas
* Whitespace fix
* Refresh after changing units
* Remove field label
* Property editor changes applied to unit system
* project to document on information, merge, util
* change project to document in unit system dialog
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Co-authored-by: WandererFan <WandererFan@gmail.com>
+ Set some properties in Document read-only
+ Implement Document::saveAs
+ Fix PropertyUUID::setValue()
+ Add a field for UUID in document information panel
