Include doc tests for solver.p_ and solver.estimate_
Include doc tests for solver.p_ and solver.estimate_

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