feat: read method that takes in arbitrary integer pixels

[kylebarron]

Change list

• New read method that takes in Window, permitting reads of partial tiles, which are then spliced together.
• fetch_tile and fetch_tiles now return Tile and list[Tile]
• Create Tile dataclass as the result of fetch_tile and fetch_tiles which holds the x and y tile indices and an array attribute, with an Array
• Create Window dataclass for holding an integer pixel window to fetch
• Update README example to use read instead of fetch_tile

For #23