It is used for search. Particularly when there are work_packages with matched journal notes.

So, for example, ```event``` is one of search results and is a work_package. Assuming it has a total of 5 notes and only two matched search query, then:

```ruby
> event.journals.count
2
> event.journals[0].version < event.journals[1].version
false
```

here order is a mess, so lets try to order by version, but

```ruby
> event.journals.order('version').count
5
```

it renders all journal notes instead of filtered by search. Filtering them again will take another query (multiplied by amount of items shown on one page of search), so:

```ruby
> event.journals.sort_by(&:version).count
2
> event.journals.sort_by(&:version).tap { |e| e[0].version < e[1].version }
true
```

no queries, just array sorting

I tried to incorporate this functionality in ```#last_journal```, but wiki_controller_tests failed immediately, so new method was introduced.