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.cpp

@@ -0,0 +1,21 @@
+#include "copium/ecs/SystemOrderer.h"
+
+#include "copium/ecs/SystemPool.h"
+
+namespace Copium
+{
+  SystemOrderer::SystemOrderer(std::type_index systemId, SystemPool* systemPool)
+    : systemId{systemId},
+      systemPool{systemPool}
+  {}
+
+  void SystemOrderer::Before(const std::type_index& otherSystemId)
+  {
+    systemPool->MoveSystemBefore(systemId, otherSystemId);
+  }
+
+  void SystemOrderer::After(const std::type_index& otherSystemId)
+  {
+    systemPool->MoveSystemAfter(systemId, otherSystemId);
+  }
+}