slippymath 0.3.0

Many function name changes in preparation for CRAN submisson. These will certainly break existing slippymath code.

I have gone with a more explicit API since I feel users will mainly use slippymath under the hood as a dependency. Therefore it is important they can understand the API quickly rather than type it quickly - since they won’t do that very often.

Function names changing: * bb_tile_extent -> bbox_tile_extent * bb_tile_query -> bbox_tile_query * bb_to_tg -> bbox_to_tile_grid * tg_composite -> compose_tile_grid * tile_bb -> tile_bbox * tg_bbs -> tile_grid_bboxes

slippymath 0.2.0