private void btnModificar_Click(object sender, EventArgs e)
 {
     Rol rol = (Rol)dtgRol.CurrentRow.DataBoundItem;
     AltaRol ar = new AltaRol(rol);
     ar.Show();
 }
 private void btnAlta_Click(object sender, EventArgs e)
 {
     AltaRol ar = new AltaRol(new Rol());
     ar.Show();
 }