Integrate SCM variables

Create a function that allows integrating aggregate properties of the SCM system.

make_scm_integrate(obj)

Arguments

obj	An object from run_scm or run_scm_collect

Details

The workflow here is to run an SCM to create an SCM by running run_scm, or a set of data from run_scm_collect and then reconstitute all the intermediate bits of data so that an any variable that PlantPlus tracks can be integrated out. Because the pre-processing step is reasonably slow, this function returns a function that takes a variable name and integrates it.