todo: Todos in the CLI like what

  Usage:

    todo                     Print todos
    todo help                Lists the available commands
    todo add Go shopping     Create a new todo item
    todo ls                  Print all pending todo items
    todo ls @tag             Print todo items containing "@tag"
    todo ls ~@tag            Print todo items not containing "@tag"
    todo ls --all            Print completed and pending todo items
    todo ls --done           Print completed todo items
    todo check 1             Mark #1 as completed
    todo mv 1 42             Change the id of given todo
    todo undo 1              Revert #1 to pending
    todo rm 1                Remove #1 item
    todo clear               Destroy all todo items
    todo clear --done        Destroy all completed todo items
    todo renumber            Re-numbers all todos starting with 1

  Environment variables:

    TODO_FORMAT=pretty                Specify formatter (simple, pretty, mini) [default: simple]
    TODO_DB_PATH=~/Dropbox/todo.json  Specify DB path [default: ~/.todo-db.json]