Adapt ErrorPage to display a proper message for UnknownIdentityException:
- This allows pages which require a session (= a logged in OwnIdentity) to throw UnkownIdentityException if the identity has been deleted meanwhile
Fix hopefully the last remaining places where to rename OwnIdentitiesPage to MyIdentityPage. Sorry.
Be more verbose in the ErrorPage explanation of UnknownIdentityException:
- Explain possible causes
- Provide the ID for debugging purposes as this shouldn't happen regularly
- Tell the user that the ID is private information