Stochastic Treatment g-formula

[pzivich]

Might be a good addition to add a stochastic treatment plan g-formula. Good preparation for me before stochastic TMLE #52 Maybe add something like .fit_stochastic()

At this point, I would only add it to the TimeFixedGFormula. Uses a re-sampling procedure. Have some parameter like resample to set. Default should be 100 or something. So stochastic fit would take the mean marginal outcome of the treatment plan

Complexities:

• [x] Easy to naive treat population at p percent. Need to think about how to implement treat those with X=x at p and those with X=y at q

[pzivich]

Added as part of v0.4.2 and will be releaseed soon

Allows for unconditional stochastic treatments and exclusive stochastic treatments. If not exclusive, TimeFixedGFormula will generate a UserWarning letting them know that the specified conditions are not mutually exclusive in their data