Constraint 2D (#147)

* Rename all Constraint by [name]Constraint3D

* Create Refs and Libraries for Constraint2D

* Remove ref to PhysWorld in Constraints ctors

* Update Constraint2d ctor to have RigiBodies first

* Add New static function for all constraints and fix an oopsie

* Add Contraint Library and remove all library useless aliases

* Add ConstraintComponent2D

* remove useless definition of Constraint2D library

* Fix : getting the world of the constraint before having created it

* Make the GetStaticBody function return a ref

* Remove : Useless AddJoint Fonction and Update CreateJoint function

* Update PhysicsSystem3D because GetStaticBody return now a ref

* Oops

* Having done something with the 3D and i was needing 2D

* Add ConstraintComponent as friend of Collision and PhysicsComponent

* Update all the Get[Static/Rigid]Body function so they return a pointer

* fix the bugs caused by the commit before

* update : CreateConstraint lambda for the nullptr case

* remove the useless  use of const pointer

* Update : CreateConstraint function

* Update ChangeLog.md

SDK/include/NDK/Components/PhysicsComponent2D.inl

@@ -307,8 +307,8 @@ namespace Ndk
 	* \return A reference to the physics object
 	*/
 
-	inline Nz::RigidBody2D& PhysicsComponent2D::GetRigidBody()
+	inline Nz::RigidBody2D* PhysicsComponent2D::GetRigidBody()
 	{
-		return *m_object.get();
+		return m_object.get();
 	}
 }