Fix usage of spatial_filter_region_node_coordinates_in_pixels in test

[rly]

Fix #19

@samuelbray32 Is this how a rectangular region should be defined? For the usage of spatial_filter_region_node_coordinates_in_pixels, are the coordinates of the last node supposed to equal the coordinates of the first node (so there should be num_nodes+1 coordinates in the list)? Or is it assumed that the polygon closes by connecting the last node to the first node, like I set up in the test here?

[samuelbray32]

Thanks for the catch. That's right, we assume closure between the last and first node without explicitly repeating the first node