Explicitly import Entry variants.
Explicitly import Entry variants.

Fixes #64.

birkenfeld/docopt.rs,brandonson/docopt.rs,zsiciarz/docopt.rs,zsiciarz/docopt.rs,birkenfeld/docopt.rs,brandonson/docopt.rs,zsiciarz/docopt.rs,birkenfeld/docopt.rs,brandonson/docopt.rs