Add of some mathematical functions

Plane: Getters and classic planes
Sphere: Getter
Vector2: Angle between two vectors
Vector3: Same in 3D

Former-commit-id: 07e6421def813743e5fd8248fe2e9503cebbb8a8

include/Nazara/Math/Vector2.inl

@@ -54,6 +54,15 @@ inline unsigned int NzVector2<unsigned int>::AbsDotProduct(const NzVector2<unsig
 	return std::labs(x * vec.x) + std::labs(y * vec.y);
 }
 
+template<typename T>
+T NzVector2<T>::AngleBetween(const NzVector2& vec, bool toDegree) const
+{
+    if (toDegree)
+        return NzRadianToDegree(std::atan2(vec.y, vec.x) - std::atan2(y, x));
+    else
+        return std::atan2(vec.y, vec.x) - std::atan2(y, x);
+}
+
 template<typename T>
 T NzVector2<T>::Distance(const NzVector2& vec) const
 {