support added for --list-properties

Changelog.md

@@ -1,3 +1,5 @@
+TODO: fix volume/mute being initialized muted
+
 ###
 
 - the [scripting wiki page](https://github.com/stax76/mpv.net/wiki/Scripting#powershell) was improved

mpv.net/mpv/mp.cs

@@ -605,12 +605,15 @@ namespace mpvnet
                                 set_property_string(left, right, true);
                         }
                         else if (!preInit && !preInitProperties.Contains(left))
+                        {
+                            if (!PrintCommandLineArgument(arg))
                             {
                                 mp.ProcessProperty(left, right);
                                 if (!App.ProcessProperty(left, right))
                                     set_property_string(left, right, true);
                             }
                         }
+                    }
                     catch (Exception e)
                     {
                         Msg.ShowException(e);
@@ -642,6 +645,20 @@ namespace mpvnet
             }
         }
 
+        static bool PrintCommandLineArgument(string argument)
+        {
+            switch (argument)
+            {
+                case "--list-properties=yes":
+                    var list = get_property_string("property-list").Split(',').ToList();
+                    list.Sort();
+                    Console.WriteLine(string.Join("\r\n", list.ToArray()));
+                    return true;
+            }
+
+            return false;
+        }
+
         public static DateTime LastLoad;
 
         public static void Load(string[] files, bool loadFolder, bool append)