ggmapinset 0.3.0

• Replaced the confusing inset_clip and inset_copy parameters of
  geom_sf_inset() with the new map_base and map_inset parameters.
• Inset frame aesthetics can now be specified consistently.
• A default inset configuration can be passed to coord_sf_inset() to avoid
  repeating it for every layer.
• Insets are now based on stat_sf_inset() which correctly adjusts the
  coordinate limits and computes some inset-related variables for downstream use.
• The new stat_sf_coordinates_inset(), stat_sf_text_inset(), and
  stat_sf_label_inset() labels complete the coverage of sf-related layers.
• Added transform_to_inset() helper for applying the inset transformation to
  arbitrary geometries (for extension developers).