`decrypt` option to remove Audible intro and outro

[vwkd]

The decrypt subcommand already has an option -s, --separate-intro-outro to separate the Audible branding into separate Intro and Outro chapters.

It would be great if there were also an option to remove them altogether.

Some previous discussion in https://github.com/mkb79/audible-cli/issues/154.

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Looking through the ffmpeg documentation, it seems the -ss [first_chapter_start] -i input.aax -to [last_chapter_end] options could be used.

There's also some examples in the wiki and more details on StackExchange.