4.17.2

- Memo for future devs: Deprecate xfce_str_replace()
- Fix document generation error
- Remove duplicate xfce_str_is_empty ()
- Move xfce_append_quoted () to xfce-string
- Remove invalid custom ngettext() macro
- Fix some GObject introspection warnings
- Add missing G_BEGIN_DECLS and G_END_DECLS
- Translation Updates:
  Catalan, Galician, Italian