Added zsh completions for grader subcommands. (#29)
Added zsh completions for grader subcommands. (#29)

* Added completions for grader subcommands.

* Added submission_id autocompletion / better assignment extraction.

* Made completion's grader home detection a bit more robust.

Now looks for GRADER_HOME, then looks in pwd, then cuts up `which
grader`.

* Some minor cleanup.

* Added inspect completions.

* Added selections for top-level verbosity.

* Assignments now complete with > 1 assignment.

* Most top-level grader --args were not allowing anything to follow them in completions.

grade-it/grader,redkyn/grader,redkyn/grader