Implement multi-contains matching algorithm. This allows a new matching method that will be the equivalent of contains on every word (delimited by space) that is given. This is the same matching algorithm used by helm in emacs and allows a way of iteratively refining your search.
drun: switch to g_app_info_should_show() for filtering This function respects OnlyShowIn and NotShowIn to filter out apps that are not applicable to the current desktop environment. It also does additional sanity checks on .desktop files, providing the same effect as the boolean expression it replaced.