NewItem-Dialog should consider Categories in search results

[pfleck]

Currently, the NewItemDialog only displays items that matches the search string. However, also categories can match the search string and should be displayed. In this case, all of the items in the category should be displayed.

For instance, the search string "Population" should display all algorithms within the "Population Based"-category.

Also, the first selected item is not the first one in the list in some cases. For instance, sometime searching for “GA” selects the “NSGA-II” instead of the “Genetic Algorithm (GA)”.