Remove redundant r SpatRaster object at terra::rasterize use (we care only
for the "geometry" of the r, so no need for new object).
Update Introduction.Rmd, README and DESCRIPTION text.
Add pkgdown website.
Add "page_rank" option on which_community argument of get_metrics.
Move figures used from README.md to man/figures.
Update README.md and Introduction.Rmd text and add badges (CRAN version, developer version, R-CMD-check and codecov).
Fix test-get_metrics.R for the upcoming 'igraph' releases, after changes on
igraph::cluster_louvain, as noted by Szabolcs Horvát (for more see
https://github.com/cadam00/priorCON/issues/1).