inria: add siconos, first import
inria: add siconos (4.2, 4.3, 4.4, 4.5) packages + also pythonocc (python bindings to opencascade) and lmgc90. Some cut and paste examples at https://github.com/siconos/guix-siconos
inria: add siconos (4.2, 4.3, 4.4, 4.5) packages + also pythonocc (python bindings to opencascade) and lmgc90. Some cut and paste examples at https://github.com/siconos/guix-siconos