Add warning that vis.myv will be removed in v0.7 (#336)
Add warning that vis.myv will be removed in v0.7 (#336)

Fixes #331
santis19/fatiando,fatiando/fatiando,drandykass/fatiando,santis19/fatiando,rafaelmds/fatiando,fatiando/fatiando,victortxa/fatiando,rafaelmds/fatiando,cmeessen/fatiando,drandykass/fatiando,victortxa/fatiando,cmeessen/fatiando