Feature requests:

1. "gobig" mode - split image into strips, scale up, add detail using
   img2img and reassemble with feathering. Issue #66.

2. Port basujindal low VRAM optimizations. Issue #62

3. Store images under folders named after the prompt. Issue #27.

4. Some sort of automation for generating variations. Issues #32 and #47.

5. Support for inpainting masks #68.

6. Support for loading variations of the stable-diffusion
   weights #49

7. Support for klms and other non-ddim samplers in img2img() #36

8. Pass a shell command to open up an image viewer on the last
   batch of images generated #29.

Code Refactorization:

1. Move the PNG file generation code out of simplet2i and into
   separate module. txt2img() and img2img() should return Image
   objects, and parent code is responsible for filenaming logic.

2. Refactor redundant code that is shared between txt2img() and
   img2img().

3. Experiment with replacing CompViz code with HuggingFace.