* feat(settings): Added Default Apps page to settings
Added a new page to settings. This page relies on xdg-mime and gio, so their existence is checked to show the page.
This logic and the mime type stuff was added to DesktopService.qml.
Slightly reordered the settings sidebar to include an Applications category
* fix(settings): read xdg-terminals.list directly
read the file directly instead of using xdg-terminal-exec which might not be installed
bbedward