Diurnal and DOW Scaling Through HEMCO for GOCART2G

[acollow]

This PR uses HEMCO to implement diurnal and day of week scaling for anthropogenic emissions and uses ExtData2G to persist emissions after 2019 without the need for duplicate emissions files for subsequent years.

[mmanyin]

@christophkeller - please remind me, are the resource files under HEMCO used at run-time or compile-time? In particular, could the files that are changing in this PR just as easily live under GOCART ?

[acollow]

This PR must be taken simultaneously with GOCART PR 216

[christophkeller]

All HEMCO*.rc files are evaluated at run-time. Moving them to GOCART2G could have some logic. This is what is done for GEOS-Chem: https://github.com/GEOS-ESM/geos-chem/tree/geos/develop/run/GEOS.
However, for GOCART2G the connectivities in GEOS_ChemGridComp.F90 need to match the names in HEMCOgocart2g_Diagn.rc. This is why we put them here in the first place.
Both approaches have their merits, I think.

[mmanyin]

Is this the point at which the yaml and rc versions of ExtData files are no longer consistent in GEOS_ChemGridComp? I think so.

[mmanyin]

@christophkeller - thanks for the rationale on rc file location

[acollow]

Yeah, the RC files can't match the capability for persisting emissions. I'm all for removing them, both from the HECMO directory and GOCART to avoid confusion but am waiting for everyone to be on the same page that they are going to disappear.