UI: Fix silent scenes with imported SL scenes

Previously, the importer assumed scenes had fields that sources did for
audio, namely volume, sync, mute and monitoring type. SL scenes do not
have these fields. This resulted in mistakes in importing, such as
imported scenes having a volume of 0.0.

This change gets rid of the non-existent fields, and explicitly sets the
volume of the scenes to 1.0 as a precaution.

UI/importers/sl.cpp

@@ -298,15 +298,8 @@ static int attempt_import(const Json &root, const string &name, Json &res)
 		Json::array filter_items = in_filters["items"].array_items();
 
 		Json in_settings = scene["settings"];
-		Json in_sync = scene["syncOffset"];
 
-		int sync = (int)(in_sync["sec"].number_value() * 1000000000 +
-				 in_sync["nsec"].number_value());
-
-		double vol = scene["volume"].number_value();
-		bool muted = scene["muted"].bool_value();
 		string name = scene["name"].string_value();
-		int monitoring = scene["monitoringType"].int_value();
 
 		Json::object out_hotkeys = Json::object{};
 		get_hotkey_bindings(out_hotkeys, hotkey_items, "");
@@ -336,11 +329,8 @@ static int attempt_import(const Json &root, const string &name, Json &res)
 				     {"id", "scene"},
 				     {"sl_id", sl_id},
 				     {"settings", in_settings},
-				     {"sync", sync},
-				     {"volume", vol},
-				     {"muted", muted},
+				     {"volume", 1.0},
 				     {"name", out_name},
-				     {"monitoring_type", monitoring},
 				     {"private_settings", Json::object{}}};
 
 		Json in_items = scene["sceneItems"];