Correct spelling error, as mentioned in issue #1.
i3: Parse and check command line arguments.

These include --add, --delete, --list, and their short forms. The
mutually exclusive property between --add and --delete was also
handled.
i3: Implement --add aux hours functionality.
i3: Implement --delete aux hours functionality.
i3: Add --list functionality.
i3: Aux hours are summed and printed with regular hours.
i3: Add aux_hours docs to header.

These docs include add/removal behavior and the aux_hours file format.
i3: Add aux_hours.json.dist file.
i3: Add confirmation on aux_hour deletion.
Closes #3: Ensure --add arg is a positive int.