Add age grids and spreading grids for Zahirovic2022 model

[michaelchin]

Update PMM to include age grids and spreading grids for Zahirovic2022 model.

And update this notebook to include Zahirovic2022 model.

[michaelchin]

I have added the seafloor age and spreading grids to the Zahirovic2022 model. See the list below.

• AgegridsUsingIsochronsMantleFrame
• AgegridsUsingIsochronsPMAG
• AgegridsUsingTopologiesMantleFrame
• AgegridsUsingTopologiesPMAG
• SpreadingRateUsingTopologiesMantleFrame
• SpreadingRateUsingTopologiesPMAG

The raster names are a bit cryptic. We should do what John has suggested. See the suggestion summary below.

• For future models, we deprecate plate model names like “Matthews2016_pmag_ref” and just have “Matthews2016”.
  And each plate model contains all its reference frames (eg, “Matthews2016” contains both PMAG and mantle).

• In both GPlately and PMM, we support the “version” argument when retrieving a plate model.

  For example…
  model = pmm.get_model("Muller2022", version=”1.1”)
  This defaults to the latest version, when not specified (eg, version “1.2.4” for Muller2022).

• In both GPlately and PMM, we add the “reference_frame” argument to those plate model functions that need it.

  For example…
  model.get_rotation_model(reference_frame=pmm.PmagReferenceFrame)
  model.get_raster(“AgeGrids”, time=100, reference_frame=pmm.PmagReferenceFrame)

• We can still support the current approach as well.

  For example…
  model.get_raster(“AgeGridsPMAG”, time=100)

• And for rasters, we add the “generated_from” argument (eg, “IsochronsOnly”, “TopologiesOnly”, etc).

  For example…
  model.get_raster(“AgeGrids”, time=100, generated_from=plate_model_manager.Isochrons)
  And we can also still support the current approach…
  model.get_raster("AgeGridsUsingIsochronsPMAG", time=100)