4.16.0

- Drop subtitles from settings dialogs (Fixes #239)
- display: Fix icon name in settings dialog
- settings-manager: Fix visibility of filterbar
- settings-manager: Correctly show/hide the filterbar
- settings-manager: Switch to GtkSearchEntry
- settings-manager: Put filter in separate bar (Fixes #226)
- appearance: Add 'Add' button to install themes (Fixes #193)
- color: Tweak colors  of icon
- mime: Accept Thunar's old id name (Fixes #247)
- settings-editor: Enable tooltips and ellipsizing for `Value` column
- settings-editor: Fix scrollbar for channels
- settings-editor: Point to correct docs URL (#245)
- bump glib (and gio, gthread, etc) minimum to 2.50.0
- Remove GSourceFunc casts
- Indentation fixes
- Translation Updates:
  Basque, Bulgarian, Estonian, French, German, Hebrew, Indonesian,
  Italian, Japanese, Norwegian Bokmål, Norwegian Nynorsk, Portuguese,
  Portuguese (Brazil), Russian, Serbian, Slovenian, Swedish, Turkish,
  Ukrainian