Search for items with project-specific annotations overriding a default value

[Nicklas Nordborg]

#2076 makes it possible to see items that have a project-specific annotation that is overriding a default value (marked with a ¤).

It would be nice to be able to search only for those annotations. For example, by adding '¤' as a suffix in the filter string the query should only match project-specific annotations. It should not be too difficult to implement given that most of the filtering is handled in the PropertyFilter class.

For single-valued annotations all tables that are needed are already part of the query. When searching for multi-valued or inherited annotations there are already multiple queries needed and I think it should be possible to find a way to implement this.

Basically, when the '¤' flag is used, the query should more or less behave as before we added support for overriding the default value. Some care is needed when used with the not equal (<>) operator since it also include items without annotations. It should not do this when it is combined with '¤'.

[Nicklas Nordborg]

(In [7340]) References #2077: Search for items with project-specific annotations overriding a default value

This seems to work now for most queries. There might be some unusual combination of query parameters that gives a strange result.

[Nicklas Nordborg]

(In [7341]) References #2077: Search for items with project-specific annotations overriding a default value

Updated the documentation to include some information about this and also the documentation for annotation types and annotation since information about project-specific annotations was missing.