Added coverage command to Makefile
Added coverage command to Makefile

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