public static unowned string** search (string search_string)
Searches desktop files for ones that match
The return value is an array of strvs. Each strv contains a list of applications that matched
search_string with an equal score.
The outer list is sorted by score so that the first strv contains the best-matching applications, and so on. The algorithm for determining
matches is undefined and may change at any time.
the search string to use