Sanitize the interface to ors_pois()

[aoles]

Modify the function interface for the sake of usability rather than strictly reflect the API. For example, abandon request argument in favor of binary summary argument, and return the category list if none arguments were provided, i.e.:

• ors_pois("pois", ...) -> ors_pois(..., summary = FALSE) (the default)
• ors_pois("stats", ...) -> ors_pois(..., summary = TRUE)
• ors_pois("list") -> ors_pois()

Additionally, ease-up things by expanding the nested geometry object into separate function arguments.

Think of a more convenient representation of the category list, or a helper function to facilitate specifying filters = list(category_ids = category)) by keywords rather than ids like in the following example.

ors_pois_ids <- function (category, group) {
  pois_list = ors_pois("list")
  
  group_ids = sapply(pois_list, `[[`, 'id')
  
  category_ids = lapply(pois_list, function(x) {
    unlist(unname(x$children))
  })
  category_ids <- do.call(c, unname(category_ids))
  if (missing(category) && missing(group))
    return(list(groups = group_ids, categories = category_ids))

  res <- list()

  if (!missing(category))
    res$category_ids <- I(unname(category_ids[category]))

  if (!missing(group))
    res$category_group_ids <- I(unname(group_ids[group]))

  res
}

ors_pois(geometry = list(geojson = list(type = "Point",
                                        coordinates = c(8.8034, 53.0756)),
                         buffer = 100),
         limit = 200,
         sortby = "distance",
         filters = ors_pois_ids(c("waste_basket", "ship")))