Made Tilesets field read only from outside the class by having it be a IReadOnlyList<TiledTileset>exposing the internal _tilesets field.
Made Tilesets field read only from outside the class by having it be a IReadOnlyList<TiledTileset>exposing the internal _tilesets field.

cra0zy/MonoGame.Extended,Aurioch/MonoGame.Extended,HyperionMT/MonoGame.Extended,LithiumToast/MonoGame.Extended,rafaelalmeidatk/MonoGame.Extended,rafaelalmeidatk/MonoGame.Extended