ggmapcn 0.3.0

NEW FEATURES

• New function: annotation_graticule()
  Adds a projection-aware global graticule system with customizable spacing, labeling, and automatic antimeridian handling.

MAJOR IMPROVEMENTS

• Major redesign of geom_world()
  Fully rebuilt global basemap system with bundled world polygons, coastlines, and boundaries; improved antimeridian handling; more reliable behavior under complex projections; and clearer, more consistent styling controls.

• Major redesign of the external data workflow (check_geodata())
  The data-management system has been rewritten to meet CRAN size limits and improve reliability. Required datasets are now located or retrieved automatically using a priority search (local directories → package extdata → user cache), with retry, resume, mirror fallbacks, and fully graceful failure. All mapping functions now call this workflow internally.

IMPROVEMENTS

• More robust CRS parsing, including reliable extraction of lon_0 from PROJ strings.
• Better stability with coord_sf(), especially for global projections and shifted central meridians.
• Updated documentation and examples, including usage of the new world dataset (world_countries.rda, world_coastlines.rda, world_boundaries.rda).
• More consistent rendering across projections such as Robinson, Mollweide, and shifted longitude systems.