Complete cross attention update

moved stable diffusion dependencies into requirements.txt
added checkout with specific commit hashes to all external repos

 Embeddings directory can't be found if running webui.py from another directory (+potential fix) #374

Fix multiple grammar & spelling errors in ReadMe

Adds NSFW content filter option

Fix #368

Swap width and height sliders in the UI

made launcher always install requirements
bumped basicsr to 1.4.2 because someone wanted it

 Codeformer face restoration not working: AttributeError: module 'modules.shared' has no attribute 'device_codeformer' #348

This reverts commit 338fb1db, reversing
changes made to c2a1b373.

Update README

Revision of the previous commit to make it less misleading and mention the option of using .bin files

Fix ugly img2img resize options

Fixes for mps/Metal: use of seeds, img2img, CodeFormer

- small update to reflect the revised commit for gradio authentication

 Instance of CUDA out of memory on a low-res batch, even with --opt-split-attention-v1 (found cause) #255

- Documented a couple of new optional flags
- Added a link to a third party repository of embeddings
- Reworded a few parts
- Fixed some typos