Replace float/UInt64 durations by a more precise Time class (#388)

Improve Clock class with atomic RestartIfOver method and allows to choose required precision

src/Nazara/Core/Systems/LifetimeSystem.cpp

@@ -8,7 +8,7 @@
 
 namespace Nz
 {
-	void LifetimeSystem::Update(float elapsedTime)
+	void LifetimeSystem::Update(Time elapsedTime)
 	{
 		auto view = m_registry.view<LifetimeComponent>();
 		for (auto [entity, lifetimeComponent] : view.each())

src/Nazara/Core/Systems/SystemGraph.cpp

@@ -11,10 +11,10 @@ namespace Nz
 
 	void SystemGraph::Update()
 	{
-		return Update(m_clock.Restart() / 1'000'000.f);
+		return Update(m_clock.Restart());
 	}
 
-	void SystemGraph::Update(float elapsedTime)
+	void SystemGraph::Update(Time elapsedTime)
 	{
 		if (!m_systemOrderUpdated)
 		{