[GUI Plugin] DjVuMakerNG -- a PDF to DjVu converter

[treeReader]

Hey everyone!
This is a fork of an older project, that has been unmaintained since 2017 had multiple incompatibilities with Python3 and modern Calibre. So I rewrote and cleaned it up to the best of my abilities, and so far, tested on Linux, it works! : I thought to upload it here too, in case anyone needs something like this, and in order to hopefully gather reports from users. I plan on testing it on Windows and Mac too, in the future, but for now I have no idea how it will act.
The plugin also has a command-line interface; can be configured to automatically convert to DjVu on import; and I added an `Options` interface that pops up after clicking the convert button and can be used to configure various parameters like DPI, quality, etc.
The plugin uses a fork of another archived project, `pdf2djvu`, that has to be built from source, but I the DjVu space is so empty nowadays that I couldn't find any better options. If you know any, please do let me know.
Anyways, you can always check the repo over at Codeberg for more details, the source and the changelog.

Installation
As I said, this plugin relies on `pdf2djvu`, which is archived, so the only option is to build the maintained fork from source.
1. Install `pdf2djvu` and Poppler utilities:

• Build the fork from source at FriedrichFroebel/pdf2djvu and add it to your `PATH`.
• Install all recommended dependencies of `pdf2djvu`.

2. Install the plugin in Calibre:

• Download the latest `.zip` from here or from the Releases page.
• Open Calibre and go to Preferences -> Advanced -> Plugins.
• Click Load plugin from file and select the downloaded `.zip`.
• Accept and restart Calibre.

Requirements: As far as I know it should work with Calibre 6.0+
Repository: https://codeberg.org/bleedingByTheFi...e-djvumaker-ng