Generate the displacement of a node (Random Walk).
[X,Y,A] = NL_M_NodeRW(X,Y,A,V,L)
Node x-coordinate (current position).
Node y-coordinate (current position).
Node angle (current angle).
Node speed.
Area side.
NL_M_NodeRW generates the displacement of the node currently located in (X,Y) in respect with the random walk mobility model. A reflection is done when the node touches each border of the network square area.