settings: refactor

- fixes programmatic slot triggering
- overhauls ui
- standardizes layouts
- fixes file path elide
- adds win10 style toggle switches
- fixes toggle state comparisons
- fixes registry settings
- fixes minimize on close function
- fixes navigate to settings from tray icon
- removes blocking calls to stopPreview
- enhances system notifications
- fixes codec selection
- fixes photobooth in settings
- fixes avatar cropping and scaling

Change-Id: I1fb7669e3cd5dc1c23743ccfe0b54c3e6ac5078b