enzo doesn't have cell sizes or positions saved

[dnarayanan]

in the pah branch:

in__ the arepo and sph tributaries we have janky code like this:

    reg.parameters['cell_size']=fw1.convert_to_units('cm') #so that we can have a uniform naming scheme for different front ends for saving in analytics/dump_data(
    reg.parameters['cell_position'] = fc1

this impacts the location of adding pah sources in pah/pah_source_create. we just need something similar added in Enzo. it's not really a big deal if Enzo doesn't have a spectrum of dust sizes in it, but this seems like a simple fix that, once we merge pah into the main branch should remember to bug @anchwr about.