Boundlexx API: An API to get all things related to Boundless

[Angellus]

• Adds URLs for Atlas/world map Images for worlds to the retrieveWorld endpoint (ex: https://api.boundlexx.app/api/v2/worlds/10/). The atlas image URLs should always be in the format https://cdn.boundlexx.app/atlas/{id}.png (ex: https://cdn.boundlexx.app/atlas/10.png)