[kernel] add comments in BlockCSRMatrix class
[kernel] add comments in BlockCSRMatrix class

fperignon/siconos,bremond/siconos,bremond/siconos,siconos/siconos,radarsat1/siconos,fperignon/siconos,bremond/siconos,bremond/siconos,fperignon/siconos,radarsat1/siconos,radarsat1/siconos,fperignon/siconos,fperignon/siconos,bremond/siconos,radarsat1/siconos,siconos/siconos,siconos/siconos,radarsat1/siconos,siconos/siconos