Add Event system

- Add abstract Event class
- Add EventDispatcher
- Add Mouse, Key and Window Events

CopiumEngine/src/copium/event/MousePressEvent.cpp

@@ -0,0 +1,13 @@
+#include "copium/event/MousePressEvent.h"
+
+namespace Copium
+{
+  MousePressEvent::MousePressEvent(int button)
+    : Event{EventType::MousePress}, button{button}
+  {}
+
+  int MousePressEvent::GetButton() const 
+  {
+    return button;
+  }
+}