Fix downloading of URLs with dashes

You can now use -- to ignore further command line arguments, allowing you to specify YouTube URLs containing dashes. We no longer default to format 18 and you can now specify just the video id in ydl if you so wish.

Optimisation and chapter prefixes

Chapters added by sponskrub are now prefixed with sponskrub- to avoid confusion, also adds some missing help info and optimises ffmpeg call.

Merge existing video metadata

Video metadata will be kept and chapters will now be adjusted as appropriate when using -chapter. Also has some typo corrections thanks to @pukkandan

Category support

Adds support for categories to sponskrub and ydl can now pass arbitrary options to sponskrub, also stops using the deprecated SponsorBlock API endpoint.

Chapter support

You now have the option to include chapters rather than removing parts of the video using the -chapter flag. ydl has been completely rewritten to facilitate this.

Both binaries are for x86_64 Linux, you will need to move them to a folder in your $PATH or ydl will not be able to find sponskrub.

Retroactive release

The first real version of sponskrub.

sponskrub is built for x86_64 Linux and ydl is just a shell script