Create different number of mesh nodes in x- and y-direction

[joeloskarsson]

Describe your changes

Currently the 2d multirange graphs created for multiscale and hierarchical graphs are restricted to laying out mesh nodes in an $n \times n$ grid. This is suitable for forecasting areas that are roughly square, but a poor choice for rectangular areas with a large difference between it's height and width.

This PR updates the way multiscale and hierarchical graphs are created to compute the refinement (or equivalently the number of mesh nodes at each level) separately in the x- and y-directions. The result of this is probably best understood by an example:

Here a mesh graph is created for an area with $10 \times 30$ grid nodes. We are making a hierarchical graph, plotting only nodes. Grid nodes have level -1. Before this change the graph would look like this:

Note that for level 0 there are 8 mesh nodes created in each direction, although this is way too many for the y-direction. This results in very short distances within the mesh in the y-direction compared to the x-direction. The higher levels share the same problem.

After this change the same graph looks like this:

Now the distance between mesh nodes is roughly the same in the x- and y-direction. Note that with this change we can no longer fit 3 mesh levels. This is actually desirable behavior, as the height of this area is actually too small to properly fit 3 levels.

This change builds upon #19 , and should be merged after that.

Issue Link

This provides some potential answers to #2. If those outstanding questions do not require further discussion I think this can close #2.

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• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📖 Documentation (Addition or improvements to documentation)

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[joeloskarsson]

Note that as this builds upon #21 the diff includes also those changes at the moment, and is not very useful. Once #21 is merged it will be more useful. Meanwhile a diff for only this PR can be found at: joeloskarsson/weather-model-graphs@archetype_changes...joeloskarsson:weather-model-graphs:coord_wise_refinement

[leifdenby]

Now the distance between mesh nodes is roughly the same in the x- and y-direction. Note that with this change we can no longer fit 3 mesh levels. This is actually desirable behavior, as the height of this area is actually too small to properly fit 3 levels.

This makes a lot of sense, and thank you for adding the example image too. It makes it really clear what the improvement is here. I will give this a proper review once #21 is in so that it easier to understand the changes that this PR uniquely introduces

[joeloskarsson]

@leifdenby Now #19 is merged, so the diff for this PR is readable 😄

[leifdenby]

Perfect! Thanks for adding the tests too! 🌟