Switch to using Tracky Mouse dwell clicker API

I designed this API in the context of JS Paint, before extracting it
to the Tracky Mouse library, so this requires minimal changes,
mostly deletions.

Author: 1j01

index.html

@@ -26,7 +26,7 @@
 	<!-- <link href="lib/os-gui/build/windows-98.css" rel="stylesheet" type="text/css"> -->
 	<!-- <link href="lib/os-gui/build/windows-default.css" rel="stylesheet" type="text/css" title="Windows Default"> -->
 	<!-- <link href="lib/os-gui/build/peggys-pastels.css" rel="alternate stylesheet" type="text/css" title="Peggy's Pastels"> -->
-	<!-- <link href="lib/tracky-mouse/core/tracky-mouse.css" rel="stylesheet" type="text/css"> -->
+	<link href="lib/tracky-mouse/core/tracky-mouse.css" rel="stylesheet" type="text/css">
 	<!--
 		@TODO: bring these styles into OS-GUI.
 		This is a custom build of 98.css https://github.com/jdan/98.css
@@ -1061,7 +1061,7 @@ <h1>Full Clipboard Support</h1>
 	<script src="lib/FileSaver.js"></script>
 	<script src="lib/font-detective.js"></script>
 	<script src="lib/libtess.min.js"></script>
-	<!-- <script src="lib/tracky-mouse/core/tracky-mouse.js"></script> -->
+	<script src="lib/tracky-mouse/core/tracky-mouse.js"></script>
 	<script src="lib/os-gui/parse-theme.js"></script>
 	<script src="lib/os-gui/$Window.js"></script>
 	<script src="lib/os-gui/MenuBar.js"></script>

src/app.js

@@ -35,7 +35,6 @@ import { TOOL_AIRBRUSH, TOOL_BRUSH, TOOL_CURVE, TOOL_ELLIPSE, TOOL_ERASER, TOOL_
 // @TODO: Minimize global variables and exports from app.js
 window.update_fill_and_stroke_colors_and_lineWidth = update_fill_and_stroke_colors_and_lineWidth;
 window.tool_go = tool_go;
-window.average_points = average_points;
 
 // #endregion