reduce mem requirements, update vanilla backbone

Update readme.md

Merge pull request #72 from johnrobinsn/main

added a couple of missing dependencies

add uniform sphere camera sampling from https://github.com/tryba/stable-dreamfusion/tree/camera_uniform_sphere

fix normal

fix https://github.com/ashawkey/stable-dreamfusion/issues/52

support negative text prompt, change to stable-diffusion v1.5

gradio: center container

gradio_app: remove unused lines

add gradio example

fix lr strategy

enable random lambertian shading in training

improve non-cuda-ray mode

Merge pull request #22 from Supercabb/docker-image