Add Operation Chaining

[DrearyWillow]

Allow users to create operation chains to perform actions back to back.
Example: epub|crop|ocr would take an epub as input, run Briss auto-cropping, and then run OCR on the Briss output.

Implementation details:

• Checkbox in settings to enable/disable. If enabled, it will appear in the buttons widget as a dropdown and button pair.
• Option to delete intermediate files
• Dropdown menu in settings, user inputs pipe delimited string with pre-defined literals. Long term, could consider another popup window as a constructor GUI. (Maybe too many pop-up windows though, I might try making draggable elements or multiple buttons to construct the string in-window.)
• Favorited chains in a json file in 'saves' folder. Maybe one file, maybe multiple, not sure yet.
• History chains saved in json file in 'saves' folder. Set max limit? Can they be the same file?

UI:

• Horizontal buttons for each operation
• Horizontal: favorite button; bar displaying current operation selection. dropdown menu can select history; execute chain button
• In settings: enable/disable, clear history, clear favorites
• Undecided: independent popup or housed between logging and filetree/buttons

[DrearyWillow]

8f572d8

[DrearyWillow]

likely add another argument to each operation indicating chaining - button toggle and what to return

[DrearyWillow]

from multiprocessing import Process

def ocrmypdf_process():
ocrmypdf.ocr('input.pdf', 'output.pdf')

def call_ocrmypdf_from_my_app():
p = Process(target=ocrmypdf_process)
p.start()
p.join()