Add Preferences menu entry

tools/level_editor/level_editor.vala

@@ -96,6 +96,7 @@ namespace Crown
 			{ "open",                 null,  "Open",             "<ctrl>O",        null, on_open             },
 			{ "save",                 null,  "Save",             "<ctrl>S",        null, on_save             },
 			{ "save-as",              null,  "Save As...",       null,             null, on_save_as          },
+			{ "preferences",          null,  "Preferences",      null,             null, on_preferences      },
 			{ "quit",                 null,  "Quit",             "<ctrl>Q",        null, on_quit             },
 			{ "menu-edit",            null,  "_Edit",            null,             null, null                },
 			{ "undo",                 null,  "Undo",             "<ctrl>Z",        null, on_undo             },
@@ -849,6 +850,10 @@ namespace Crown
 			save_as();
 		}
 
+		private void on_preferences(Gtk.Action action)
+		{
+		}
+
 		private void on_quit(Gtk.Action action)
 		{
 			quit();

tools/ui/level_editor_menu.xml

@@ -7,6 +7,8 @@
 			<menuitem action="save"></menuitem>
 			<menuitem action="save-as"></menuitem>
 			<separator></separator>
+			<menuitem action="preferences"></menuitem>
+			<separator></separator>
 			<menuitem action="quit"></menuitem>
 		</menu>
 		<menu action="menu-edit">