ggmap 4.0.0

New features

Adds support for all styles from Stadia Maps via get_stadiamap() (thanks @ianthetechie, #351).

Stamen map tiles are now hosted by Stadia Maps (see http://maps.stamen.com/stadia-partnership/), which necessitates some breaking changes in ggmap. The existing URLs are expected to be shut off after October 31, 2023. This release renames the Stamen-related functions to Stadia equivalents (ex: get_stamenmap() is now get_stadiamap()). Developers will also need to make some minor changes to the style names to include a stamen_ prefix and convert the names to snake_case. For example toner-lite becomes stamen_toner_lite.
Removes the toner hybrid layer group, as well as some other deprecated styles which were not in wide use. Stamen's Toner Hybrid can be recreated by layering the lines and labels on top of each other.
Adds styles from Stadia Maps: Alidade Smooth (light and dark) and Outdoors.
ggmap no longer depends on RgoogleMaps (thanks @sanjmeh, #354).

geocode_cache() is now exported to the user, and functions write_geocode_cache() and write_geocode_cache() exist to facilitate using the same cache across sessions.

ggmap no longer depends on rjson (thanks @MichaelChirico, #317).
Most functions now use cli-based messaging functions, following ggplot2's lead.

ggmap functions can now be called even if it has not been attached to the search path (loaded) (reported by @jennybc, @lorenzwalthert, #264, #244).
Google functions now properly encode #'s (reported by @aaronrudkin, #272).
get_stamenmap() now only returns URLs if messaging = TRUE (Reported by @ikosmidis, #274). It also includes a more formal attribution to Stamen Design and OpenStreetMap.
get_stamenmap() now supports a SSL Stamen endpoint via the https argument (#276).
mapdist() now properly orders results (reported by @BirgerNi, #266).
mapdist() now properly returns URLs if urlonly = TRUE.
get_map() now (again) respects the source = "google" specification when given a bounding box (reported by @julovi, #267).
geocode() now (again) respects the source = "dsk" specification (reported by @alistaire47, #180).
A bug giving an error message Error in aperm.default(map, c(2, 1, 3)) : invalid first argument, must be an array has now been fixed. (solution by @kent37, #262).
geocode() now properly caches when geocoding several locations. The caching keys are now the hash values of the scrubbed url.