Adjustment term specification for analysis models

[erex]

There are no arguments to make.ds.analysis that allows the user to specify adjustment terms. I don't know how often users will want to explore models with adjustment terms, so it might not be a big deal. Of course if there are covariates in detection functions, the adjustment terms would be shut off.

• it this intentional?
• class DS.Analysis carries slots for adjustments
• the call to ds carries an adjustments argument

[LHMarshall]

I cannot neatly add new slots to classes later so the slot was created so that this can be implemented at a later date.

When this is implemented the option to enforce strict monotonicity will also need to be implemented for stability. See this issue