Find transition firing order
tran = firingorderbig(node_tree,id_parent_tran,forward,backward,mark,idnode)
This function is used to find transition firing order to reach state where that state covers mark. The different between firingorder and firingorderbig is the output. Function firingorder returns all possibilities with same number of firing but function firingorderbig returns one transition firing order. Function firingorder needs bigger memory than this function.