Started implementing PEL
Started implementing PEL

Not much progress yet.

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