PEP 8 ok and density option fixed
PEP 8 ok and density option fixed

victortxa/fatiando,rafaelmds/fatiando,santis19/fatiando,rafaelmds/fatiando,cmeessen/fatiando,fatiando/fatiando,mtb-za/fatiando,drandykass/fatiando,cmeessen/fatiando,santis19/fatiando,mtb-za/fatiando,fatiando/fatiando,victortxa/fatiando,drandykass/fatiando