Add Scene with systems

- Add Scene class which populates the engine with Systems which handles
  all logic in the game
- Add Systems to ecs

CopiumEngine/src/copium/example/Components.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include "copium/asset/AssetRef.h"
+
+#include <string>
+
+#include <glm/glm.hpp>
+
+namespace Copium
+{
+  struct TransformC
+  {
+    glm::vec2 position;
+    glm::vec2 size;
+  };
+
+  struct ColorC
+  {
+    glm::vec3 color;
+  };
+
+  struct TextureC
+  {
+    AssetRef asset;
+    glm::vec2 texCoord1;
+    glm::vec2 texCoord2;
+  };
+
+  struct TextC
+  {
+    AssetRef font;
+    std::string text;
+    float fontSize;
+  };
+
+  struct MouseFollowC
+  {};
+
+  struct FrameCountC
+  {};
+}