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

src/app/qtkscene.h

@@ -0,0 +1,75 @@
+/*##############################################################################
+## 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>
+
+/**
+ * Example scene using QtkWidget to render 3D models and simple geometry within
+ * QtOpenGLWidgets. This scene also shows some examples of using GLSL shaders to
+ * apply the basic lighting techniques leading up to Phong.
+ *
+ * The Qtk::Scene base class provides containers for N pointers to MeshRenderer
+ * and Model objects. We can create and insert as many as we like within this
+ * child class implementation. This child class does not need to manually draw
+ * objects inserted into these containers. The child class would only need to
+ * update uniform or other data that may change per-frame.
+ * See scene.h and `init()` for more information.
+ *
+ * To modify the scene objects should be initialized within the `init()` public
+ * method. Any required movement or updates should be applied within `draw()` or
+ * `update()`.
+ *
+ * To create your own Scene from scratch see Qtk::Scene.
+ */
+class QtkScene : public Qtk::SceneInterface {
+  public:
+    /***************************************************************************
+     * Contructors / Destructors
+     **************************************************************************/
+
+    QtkScene(Qtk::Scene * scene);
+
+    ~QtkScene();
+
+    /***************************************************************************
+     * Inherited Public Overrides
+     **************************************************************************/
+
+    /**
+     * Initialize objects within the scene
+     */
+    void init() override;
+
+    /**
+     * Called when OpenGL repaints the widget.
+     */
+    void draw() override;
+
+    /**
+     * Called when the Qt `frameSwapped` signal is caught.
+     * See definition of `QtkWidget::initializeGL()`
+     */
+    void update() override;
+
+  private:
+    /***************************************************************************
+     * Private Members
+     **************************************************************************/
+
+    // Additional example objects created within this example.
+    // + The base class Scene manages objects stored within mMeshes or mModels
+    Qtk::MeshRenderer * mTestPhong {};
+    Qtk::MeshRenderer * mTestSpecular {};
+    Qtk::MeshRenderer * mTestDiffuse {};
+    Qtk::MeshRenderer * mTestAmbient {};
+};
+
+#endif  // QTK_EXAMPLE_SCENE_H