Add an option to inline all libraries used in a given DSP

[sletz]

• So that to obtain a self-contained file. Note that with would be different from the current -e option that exports an expanded but somewhat unreadable DSP file.
• Recursive library import must be implemented
• The code used to handle the -i option can probably be reused for that

[dfl]

attempted this here https://github.com/dfl/faust/tree/feature/inline-libraries