Stabilise MoveToWorld (#4004)

* Stabilise MoveToWorld

* Fix comments and deprecate ScheduleMoveToWorld

* Enhanced thread safety for m_WorldChangeInfo

* Return unique_ptr from cAtomicUniquePtr::exchange

* cWorld now calls entity cEntity::OnAddToWorld and cEntity::OnRemoveFromWorld.

Allows broadcasting entities added to the world from the world's tick thread.
This also factors out some common code from cEntity::DoMoveToWorld and cEntity::Initialize.

As a consequence, cEntity::Destroy(false) (i.e. Destroying the entity without broadcasting) is impossible.
This isn't used anywhere in Cuberite so it's now deprecated.

* Update entity position after removing it from the world.
Fixes broadcasts being sent to the wrong chunk.

* Fix style

* cEntity: Update LastSentPosition when sending spawn packet

* Add Wno-deprecated-declarations to the lua bindings

* Kill uses of ScheduleMoveToWorld

src/Entities/Pickup.cpp

@@ -156,7 +156,7 @@ void cPickup::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 				m_Timer += a_Dt;  // In case we have to destroy the pickup in the same tick.
 				if (m_Timer > std::chrono::milliseconds(500))
 				{
-					Destroy(true);
+					Destroy();
 					return;
 				}
 			}
@@ -180,14 +180,14 @@ void cPickup::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 	{
 		if (m_Timer > std::chrono::milliseconds(500))  // 0.5 second
 		{
-			Destroy(true);
+			Destroy();
 			return;
 		}
 	}
 
 	if (m_Timer > m_Lifetime)
 	{
-		Destroy(true);
+		Destroy();
 		return;
 	}
 }
@@ -200,7 +200,7 @@ bool cPickup::DoTakeDamage(TakeDamageInfo & a_TDI)
 {
 	if (a_TDI.DamageType == dtCactusContact)
 	{
-		Destroy(true);
+		Destroy();
 		return true;
 	}