config/Templates: add attribute "deprecated"

src/config/ConfigTemplates.cxx

@@ -70,9 +70,9 @@ const ConfigTemplate config_param_templates[] = {
 	{ "gapless_mp3_playback" },
 	{ "auto_update" },
 	{ "auto_update_depth" },
-	{ "despotify_user" },
-	{ "despotify_password" },
-	{ "despotify_high_bitrate" },
+	{ "despotify_user", false, true },
+	{ "despotify_password", false, true },
+	{ "despotify_high_bitrate", false, true },
 };
 
 static constexpr unsigned n_config_param_templates =

src/config/ConfigTemplates.hxx

@@ -24,9 +24,14 @@ struct ConfigTemplate {
 	const char *const name;
 	const bool repeatable;
 
+	// TODO: print warning when a deprecated option is used
+	const bool deprecated;
+
 	constexpr ConfigTemplate(const char *_name,
-				 bool _repeatable=false)
-		:name(_name), repeatable(_repeatable) {}
+				 bool _repeatable=false,
+				 bool _deprecated=false)
+		:name(_name), repeatable(_repeatable),
+		 deprecated(_deprecated) {}
 };
 
 extern const ConfigTemplate config_param_templates[];