Basic documentation for custom_code.py template

Block event propagation when lightbox is triggered

Fix gallery not scrolling left

Make image gallery bigger on 2k+ displays

image info tab

* Fix process_images where the number of images is not a multiple of (batch_size * n_iter), which would cause us to throw an exception.
* Add a textbox option to Prompts from file (ease of use and it makes it much easier to use on a mobile device)
* Fix the fact that Prompts from file was sometimes passing an empty batch.

Reverse run_pnginfo for compatibility reasons

the last PR broke saving EXiF completely for me. I don't know if it was broken already or some condition changed, but it seems like the person who originally added EXIF said, saving it with PIL may not work. I switched to using piexif to add data after the file written.

* image.save takes exif as a parameter
* piexif takes the bytes as a parameter, not the exif_bytes function itself
* reduce calls to create_exif_bytes

As it is currently, txt2img and img2img send back the previous output args (txt2img_gallery, generation_info, html_info) whenever you generate a new image. This can lead to uploading a huge gallery of previously generated images, which leads to an unnecessary delay between submitting and beginning to generate.