include/merge trollop-subcommands

I found this awesome gem, trollop-subcommands, that extends trollop with a better interface for creating subcommands. I wonder if we should somehow merge this into trollop directly? https://github.com/jwliechty/trollop-subcommands @jwliechty What do you think since you're the author of the gem?

Start by reviewing the trollop-subcommands gem linked in the issue and comparing its subcommand interface with optimist. The issue names no repository files or tests and does not define the merge scope; done would require an agreed design and explicit integration plan.

Written by the indexing model from the issue text.