traveltime 1.0.0

• First CRAN release.
• calculate_travel_time() now uses terra::costDist() internally, removing the dependencies on the superseded raster and gdistance packages. Results are effectively the same; see the validation article for details of the small differences.
• Cells that cannot be reached from any of points (e.g. because they are cut off by NA cells) are now NA in the output of calculate_travel_time(). Previously they were Inf.
• calculate_travel_time() now drops (with a warning) any points that fall outside friction_surface, and errors if none fall within it.
• calculate_travel_time() now works with a single point supplied as a one-row matrix or a one-point SpatVector. Previously these errored.
• ext_matrix(), and so get_friction_surface(), now accept integer as well as double vectors for extent.
• calculate_travel_time() and get_friction_surface() now correctly return the existing file when filename already exists and overwrite = FALSE, as documented. Previously they warned and then errored.
• get_friction_surface() now fails gracefully, returning NULL with a warning, if the friction surface cannot be downloaded.
• Removed unused dependency on lifecycle.