command: add options to property list

Now options are accessible through the property list as well, which
unifies them to a degree.

Not all options support runtime changes (meaning affected components
need to be restarted for the options to take effects). Remove from the
manpage those properties which are cleanly mapped to options anyway.
From the user-perspective they're just options available through the
property interface.

player/main.c

@@ -303,6 +303,10 @@ static bool handle_help_options(struct MPContext *mpctx)
         ao_print_devices(mpctx->global, log);
         opt_exit = 1;
     }
+    if (opts->property_print_help) {
+        property_print_help(mpctx);
+        opt_exit = 1;
+    }
 #if HAVE_ENCODING
     if (encode_lavc_showhelp(log, opts->encode_opts))
         opt_exit = 1;