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/ecs/SystemOrderer.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <vector>
+#include <map>
+#include <typeindex>
+
+namespace Copium
+{
+  class SystemPool;
+
+  class SystemOrderer
+  {
+  private:
+    std::type_index systemId;
+    SystemPool* systemPool = nullptr;
+  public:
+    SystemOrderer(std::type_index systemId, SystemPool* systemPool);
+
+    template <typename Other>
+    void Before()
+    {
+      Before(typeid(Other));
+    }
+
+    template <typename Other>
+    void After()
+    {
+      After(typeid(Other));
+    }
+
+  private:
+    void Before(const std::type_index& otherSystemId);
+    void After(const std::type_index& otherSystemId);
+  };
+}