assim.batch: move get.da.data.growth.R and get.da.data.R to inst folder

[infotroph]

Looking at those functions, I suspect get.da.data.growth.R and get.da.data.R can both be moved from the /R folder to the /inst folder. I don't have time to go through all the code in detail, but I think most of what's here is redundant with newer code by @istfer and others. This code doesn't appear to be operationally linked to other bits of the PDA and the value of retaining this code is primarily because it provides a record of what Carl Davidson did in his (still unpublished) Master thesis.

Originally posted by @mdietze in #3200 (comment)