Changes in version 0.3.0                        

  - Breaking: dropped the stdt S3 wrapper class (list(stdt = <table>,
    crs = <chr>)). All functions (generate_cv_index(),
    generate_spt_index(), generate_block_sp_index(), plot_cv_folds(),
    convert_cv_index_rset()) now take a plain data.frame-like object
    (e.g. the output of prep_input()) with lon, lat, and time columns
    directly, and always return a fold vector matching that object's row
    count. spdat is now a data.table with a "crs" attribute instead of a
    wrapped list.
  - generate_block_sp_index() now clusters/joins on unique lon/lat
    locations and broadcasts the result back onto all rows, instead of
    operating on every row. This keeps spatial blocking correct for
    irregular/unbalanced spacetime panels (e.g. stations observed a
    different number of times) and fixes the sf/SpatVector polygon-block
    path, which previously received the whole wrapped stdt object
    instead of a table sf::st_as_sf() could consume.

                         Changes in version 0.2                         

  - Added multiple backend engines for spatial blocking
  - Added plot function
  - Added preparation function

                         Changes in version 0.1                         

  - Subset the indexing functions from amadeus