Improve Epub metadata parsing (read_text) and strip html tags from desc

[jlaunay]

Description was missing for most of my books.
I updated the parse_opf_metadata() function to use read_text() and extract the fields correctly and I also added strip_html_tags() to clean the descriptions.

I tested it on my collection and now I have a description for every book.

[paviro]

Thank you will look into it later today!

[paviro]

Made some changes, please have a look and tell me what you think.

I also think we should maybe keep some of the html tags no?

[paviro]

Funny that I didn't even notice that at some point all the descriptions seem to have vanished 🙈

[jlaunay]

I just tested the changes you made to my fix and it's perfect!
Even better since you keep the formatting.
When I saw there was a bug, instead of opening an issue, I preferred to try contributing and fixing it myself.
I went with the simplest solution by removing all the tags 😉

Thanks again for your reactivity!

"Although KOReader supports more than just EPUBs, this tool does not, and probably never will, as I don't use them and this is a weekend project that probably won't be maintained much."

PS: I think you can remove this sentence in the README.md now 🤣

[paviro]

I love that you did! Not only did you find the issue that I didn't see haha you also fixed it! I also fixed some issues with escaped & etc in genre tags.

Haha true yes I probably can :D but I still think I proably will only support epub :D