UPBGE: Fix object matrix when replacing mesh.

Previously the mesh user matrix, the matrix used in rendering,
was updated in KX_GameObject::UpdateBuckets. But only when the
scene graph node was modified. This doesn't covered a case:
if the object mesh is replaced and that the object doesn't
move.
In this case the matrix is left uninitialized as the mesh user
is recreated. To solve this issue an initialization of the
matrix is proceeded into AddMeshUser.
The other datas in RAS_MeshUser don't need this behaviour because
they are update without condition in UpdateBuckets.

source/gameengine/Ketsji/KX_FontObject.cpp

@@ -130,6 +130,7 @@ void KX_FontObject::AddMeshUser()
 {
 	m_meshUser = new RAS_TextUser(m_pClient_info, m_boundingBox);
 
+	// Make sure the mesh user get the matrix even if the object doesn't move.
 	NodeGetWorldTransform().getValue(m_meshUser->GetMatrix());
 
 	RAS_BucketManager *bucketManager = GetScene()->GetBucketManager();

source/gameengine/Ketsji/KX_GameObject.cpp

@@ -715,6 +715,8 @@ void KX_GameObject::AddMeshUser()
 {
 	for (size_t i = 0; i < m_meshes.size(); ++i) {
 		m_meshUser = m_meshes[i]->AddMeshUser(m_pClient_info, GetDeformer());
+		// Make sure the mesh user get the matrix even if the object doesn't move.
+		NodeGetWorldTransform().getValue(m_meshUser->GetMatrix());
 	}
 
 	if (m_meshUser) {