List of matrices format for multivariate ranks

[Quentin62]

In the multivariate case, the different dimension are concatenated in a matrix.
It would be more convenient to use list of matrices

Current format (big4 data):

          A.uefa B.uefa C.uefa D.uefa A.pl B.pl C.pl D.pl
1992-1993      1      2      3      4    1    2    3    4
1993-1994      1      3      2      4    1    3    2    4
1994-1995      1      3      2      4    1    2    4    3
1995-1996      1      3      2      4    1    2    3    4
1996-1997      1      2      3      4    1    3    2    4

New accepted format:

[[1]]
          A.uefa B.uefa C.uefa D.uefa
1992-1993      1      2      3      4
1993-1994      1      3      2      4
1994-1995      1      3      2      4
1995-1996      1      3      2      4
1996-1997      1      2      3      4

[[2]]
          A.pl B.pl C.pl D.pl
1992-1993    1    2    3    4
1993-1994    1    3    2    4
1994-1995    1    2    4    3
1995-1996    1    2    3    4
1996-1997    1    3    2    4

One advantage is to get rid of the m argument