Pygeogrids

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- FIX: Nearest neighbour search for grids with non-default GPIs
- Replace Travis CI with Github Actions workflows.

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- Add k parameter to nearest neighbor search (number of nearest neighbors to return)

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- Refracture package to pyscaffold 3 standard

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- Allow subsetting from non-binary masks
- Fix ParallelArcDist function (two calls of deg2rad(lat))
- Update readme
- Update to PyScaffold 2.5.9

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- Fix speed bug of gpi2cell
- Update copyright header

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- Add option to subset a grid with a shape file (OGRGeometry) in
get_shp_grid_points.
- Add shapefile module for reading shapefiles from
http://biogeo.ucdavis.edu/data/gadm2.8/gadm28_levels.shp.zip by Global
Administrative Level
- Ensure that `get_bbox_grid_points` returns points while taking cell order into
account.