Change search to use action bar filter, rather than new Activity
Currently, when pressing the search menu item in the main list of apps, it overlays a new activity on top of the app list to display the search results. Instead of this, it should filter the results in place. This is similar to how most search takes place in Android apps these days, and should be familiar to most users.
I'm not 100% sure yet, but it would potentially be nice to be able to filter every list individually too. That is, if you are viewing the "Installed" tab and you start searching, it will filter that list.
This would also solve Issue #293 (closed) by always returning to the main list. In order to make it work as expected, though, it should probably take into account #57 (closed) (Save input between searches).