Add `dose()` and remove `podo()`

[mattfidler]

https://github.com/nlmixrdevelopment/RxODE/issues/314

And add evid for transit-compartment type models

[billdenney]

It's not totally clear to me what this addition is. I think that having the ability to pull all dose-related information information from the last dose makes sense (and, I think that's what this is moving toward).

(I'm not trying to expand the scope of this if it's unrelated. I am trying to expand the scope of it so that it covers the complete need, if it is related.)

The dose-related columns that I can think of and their closely-related derived values are:

• Dosing compartment
• Time of dose start
• Time since dose start
• Time of dose end (for infusions)
• Time since dose end (for infusions)
• Amount of dose
  • Should we consider something about bioavailability of the dose?
• Rate of infusion
• Duration of infusion
• Is it steady-state dosing?

We would want to account for II and ADDL within this, too. It's not clear to me if we would do that by always having the above information relative to the most recent dose if there are II and ADDL in the data or if there should be an option to choose the time when the dose was initially-specified (i.e. the first of the II/ADDL doses) and an option to choose the most recent. (I don't see a lot of value to going back to the initially-specified dose, but I think it's good to consider the option and explicitly reject it rather than not consider it.)

[mattfidler]

This is mostly to support transit compartments but...

• Time of dose start -- already available tlast, tlast(), tlast(cmt)
• Time since dose start -- already available tad, tad(), and tad(cmt)
• Time of dose end (for infusions) Not yet available, should be a separate issue
• Time since dose end (for infusions) Not yet available, should be a separate issue
• Amount of dose (this request); will be dose dose() and dose(cmt)

The others are questions:

• Should we consider something about bioavailability of the dose? Perhaps, but I am unsure how for now
• Rate of infusion
• Duration of infusion
• Is it steady-state dosing?

[mattfidler]

Also available is time since first dose tafd, tafd(), tafd(cmt)

[mattfidler]

Forgot there is also the dose number: dosenum()

[mattfidler]

For Monolix:

https://mlxtran.lixoft.com/language-reference/dose-related-keywords/