Add GEFS programs

[WalterKolczynski-NOAA]

Adds the four programs from the legacy GEFS system that I think will be needed in the combined global workflow. The source code is unchanged, though some directories and one source file has been renamed to remove prefixes.

• ensadd: Extends grib2 header information to include ensemble info
• ensppf: Calculates ensemble precip probability forecast
• ensstat: Computes mean and spread for atmosphere grib2 files
• wave_stat: Computes mean, spread, and prob for wave grib2 files

Resolves #51 Refs NOAA-EMC/global-workflow#2296

Build tested and successful on:

• Orion
• Hera
• WCOSS2

[BoCui-NOAA]

Here are some clarifications for code ensadd.f

gfldo%ipdtmpl(16)=ienst ( 0 for Unperturbed High-Resolution Control Forecast )
gfldo%ipdtmpl(17)=iensi ( Perturbation number , 0 for gfs forecast )
gfldo%ipdtmpl(18)=10   ( Number of forecasts in ensemble)

The gfldo%ipdtmpl(18) come from Octect no 36 in https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp4-1.shtml

Use "wgrib2 -ens" to check ensemble files that don't display the ensemble size information. The ensemble size information will be saved and transferred to probability forecasts, mean or spread and ect , i.e how many members are used to do the calculation to get these products.

For gfs forecast, choosing " gfldo%ipdtmpl(18)=30" will let the ensemble size information consistent with the GEFS member. However its setting won't affect the gefs mean and spread products' grib2 message for gfs files are not included to do mean/spread calculation.

This is a small change in ensadd.f. you can fix it later.