Add a wrapper for wgrib2 in Herbie.

[blaylockbk]

TLDR; This pull requests lays the foundation for using the wgrib2 in Herbie by building a wgrib2 wrapper.

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wgrib2 is a powerful command line utility for working with GRIB2 files. It is not easily installable on Windows. Still, including this wrapper will let Herbie help someone use wgrib2, if it is installed.

Note: wgrib2 can be installed for linux from conda-forge.

from herbie.wgrib2 import wgrib2

# Print the path to the wgrib2 executable
print(wgrib2.wgrib2)

# Create an inventory of a downloaded GRIB2 file (return inventory as a string).
wgrib2.inventory("/path/to/file.grib2")

# Create a regional subset of a file
wgrib2.region("/path/to/file.grib2", extent=(-100,90,30,40))

# Check if vector quantities are earth or grid relatvie
wgrib2.vector_relative("/path/to/file.grib2")

Class Methods

• Create an inventory of a downloaded GRIB2 file (returns inventory as a string).
• Create inventory files for a GRIB2 file (returns nothing, just saves files to disk).
• Make geographical area subsets (Fixes Add interface to wgrib2 to produce subset #109)
• Determine if wind vectors are "earth-relative" or "grid-relative"

TODO

• Use this new wrapper in the Herbie class.
• Update tests to use the new wrapper.