Improve math module (#396)

* Improve math module

- Mark almost everything constexpr
- Equality (a == b) is now exact, down to the bit level. If you want approximate equality use the new ApproxEqual method/static method
- Rename Nz::Extend to Nz::Extent
- Removed Make[] and Set[] methods in favor of their static counterpart and operator=

include/Nazara/Math/PidController.hpp

@@ -13,9 +13,9 @@ namespace Nz
 	class PidController
 	{
 		public:
-			PidController(float p, float i, float d);
+			constexpr PidController(float p, float i, float d);
 
-			T Update(const T& currentError, float elapsedTime);
+			constexpr T Update(const T& currentError, float elapsedTime);
 
 		private:
 			T m_lastError;