duply: New completion

[jose1711]

No description provided.

[scop]

A very brief review, just to get some obvious things out of the way:

• Most importantly: have you considered and/or tried submitting this for inclusion with upstream duply instead of here? Especially with the lists of hardcoded commands, chained command, and options, this would be better placed there.
• Coding style (indentation amount, use of line wrapping after if etc, is not consistent with the rest of our completions.
• Should use our _init_completion mechanism.
• Leakage of variables (local missing): commands, chained_commands, may_continue, comp_commands, sep, command and probably some more.
• Test suite addition missing.