Setting empty envars causes the `os.environ.get('ENVAR', "some default")` pattern in launch.py to ignore it's fallback value.

* fix for odd error only in webp files whereby piexif.insert inserts the bytes correctly, but image.save inserts extra "Exif" in the image metadata which results in an error on reading

Fixes an issue where it's still possible to write to arbitrary directories through careful use of \.. or /.. in directory patterns

...and fix the regex to work better

reeeegex

added the ability to use {prompt} in styles
added a button to apply style to textbox
rearranged top row for UI

Better code

Handles grids names. Code more robust and doesn't fail if mixed with other files.

Better computing of images indexes in filenames

* UserComment needs an ID code at the start of the tag area. This is provided by piexif.helper.UserComment, otherwise an "Warning 	 Invalid EXIF text encoding for UserComment" is thrown upon reading the exif data

loopback moved to scripts, added support for multiple batches, changed to honor save grids and how grids in web setting