refactored image paste handling to fill unset images successively, then replace last existing image (fixes #981)

Fixed grids saving to subdirectory when the setting is unchecked but "save images to subdirectory" was checked.

Fix by @MrAcademy

copy over fields when sending to img2img: https://github.com/AUTOMATIC1111/stable-diffusion-webui/issues/1029

added more robust detection of last line with parameters for pasted prompts

removing duplicated requirements (transformers, diffusers) and reorganizing alphabetically to be able to spot duplicates in the future.

Prevent writing to arbitrary directories, as usual

 Fix to XY_Grid script console progress bar and other progress bar improvements #890