Hyoga

This release turns hyoga into more than just a visualization tool. Two functions were added to [open](https://hyoga.readthedocs.io/en/stable/datasets/opening.html) online elevation data ([GEBCO](https://www.gebco.net/)) and monthly climatologies ([CHELSA](https://chelsa-climate.org/)) in custom projections that can be used as [PISM](https://pism.io/) input files for paleoglacier modelling about anywhere on Earth. Minor bugs were fixed. Code coverage decreased to 67 percent.

This release implements profile [interpolation](https://hyoga.readthedocs.io/en/stable/datasets/masking.html) and scale bars, both documented in new [examples](https://hyoga.readthedocs.io/en/stable/examples/index.html#), and fixes a bug in grid interpolation to axes coordinates. Continuous integration has been improved with lazy tests for all plot methods, and monitoring of code coverage, increased from 33 to 73 percent in this release.

This release removes the required dependency on [cartopy](https://scitools.org.uk/cartopy/) by implementing own downloaders for Natural Earth and other (and future) data. All dependencies, and the docs, can be built with pip. Plot methods set aspect ratio to equal, and coordinate labels are hidden by default. Development has moved on a feature-branch squash workflow (as [xarray][https://xarray.dev) and [geopandas](https://geopandas.org)).

This is a major relase implementing several cartographic features. It adds custom colormaps and plot methods for [shaded reliefs](https://hyoga.readthedocs.io/en/stable/datasets/shading.html), and an interface to [open and plot](https://hyoga.readthedocs.io/en/stable/datasets/vectors.html) Natural Earth data and paleoglacier extents. The documentation uses a new theme. A logo and new [examples](https://hyoga.readthedocs.io/en/stable/examples/index.html) were added. The package structure has been reworked to better serve [future plans](https://hyoga.readthedocs.io/en/stable/roadmap.html).

This release includes better masks and a dependency on [cf_xarray](https://cf-xarray.readthedocs.io). Plot methods now search for standard variable `land_ice_area_fraction` for masking and default to using a configurable ice thickness masking point. Masking with `where` remains available and a new [documentation page](https://hyoga.readthedocs.io/en/latest/masking.html) explains masking features.

This release includes bug fixes and documentation improvements, including more lightweight demo data. There are new examples in the gallery demonstrating the computation of bedrock isostatic adjustment from a reference topography, and interpolating model results on higher-resolution topography for enhanced visualization.