Return a list of ranked motifs. Each motif contains the information [isaxcode, recmatrix, vectst, rank], as described:
isaxcode: Motif sequences in character format
recmatrix: Matrix giving as information the blocks containing this motif
vectst: Coordinate of the start positions of the motif in the original dataset
rank: L of information used for motif ranking, as [dist, word, qtd, proj]