add "next use" facilities to DES and to CostGraph

[rjhanes]

Ported from https://github.nrel.gov/aeberle/celavi/issues/195

This issue is being addressed in branch issue195

Previous commit on this issue is 8b70d49

[rjhanes]

Running commit bfd3e33 on tiny-data with artificially low recycling costs:

costgraph_parameters:
    sc_begin: manufacturing
    sc_end: 
    - landfilling
    - cement co-processing
    - next use
    cg_verbose: 1
    save_cg_csv: True
    finegrind_cumul_initial: 1.0
    finegrind_initial_cost: 10.0
    finegrind_revenue: 50.0
    finegrind_learnrate: -0.05
    finegrind_material_loss: 0.3
    coarsegrind_cumul_initial: 1.0
    coarsegrind_initial_cost: 10.0
    coarsegrind_learnrate: -0.05
    cg_update_timesteps: 12

produced the following blade counts:

which looks promising.

Still need to test on medium-data and/or a filtered version of develop before merging.

[rjhanes]

Closed with PR #50