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/Utility/Systems/SkeletonSystem.cpp

@@ -23,7 +23,7 @@ namespace Nz
 		m_skeletonConstructObserver.disconnect();
 	}
 
-	void SkeletonSystem::Update(float /*elapsedTime*/)
+	void SkeletonSystem::Update(Time /*elapsedTime*/)
 	{
 		m_sharedSkeletonConstructObserver.each([&](entt::entity entity)
 		{