restructure "existing excerpts" option groups
Created by: das-g
Now that the option to make newly created excerpts public has been removed (#685 (closed)), re-structure the choice groups for existing excerpts to create exports from:
- Join "Personal public excerpts" (public excerpts owned by the logged in user) and "Other excerpts" (public excerpts owned by others) to just "Public excerpts"
Rationale
When administrators turn an excerpt public, they will probably also appropriate it, so that most normal users won't ever have public excerpts owned by themselves.
Also
- While we're at this, let's also re-label "Countries" to "Countries and administrative areas" to better fit that option group's content.