bug in dataset_readers.py

[yuzhongruicn]

Hi!
Thanks for the great work.
For those who want to try non-square image, there is a little bug in

LucidDreamer/scene/dataset_readers.py

Line 358 in 76ed990

fovy = focal2fov(fov2focal(fovx, image.size[1]), image.size[0])

which shoud be
fovy = focal2fov(fov2focal(fovx, image.size[0]), image.size[1])