Improve cmake and GUI (#13)

+ Packaging and CI for Windows, Mac, Linux
+ Debian package, NSIS Windows installer, OSX appbundle
+ Example application using libqtk
+ Component installation for `qtk`, `libqtk`, or `collection` with cmake

example-app/examplescene.h

@@ -0,0 +1,27 @@
+/*##############################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2023 Shaun Reed, all rights reserved                ##
+## About: Example Qtk scene                                                   ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+##############################################################################*/
+
+#ifndef QTK_EXAMPLE_SCENE_H
+#define QTK_EXAMPLE_SCENE_H
+
+#include <qtk/scene.h>
+
+class ExampleScene : public Qtk::SceneInterface {
+  public:
+    ExampleScene(Qtk::Scene * scene);
+
+    ~ExampleScene();
+
+    void init() override;
+
+    void draw() override;
+
+    void update() override;
+};
+
+#endif  // QTK_EXAMPLE_SCENE_H