Better syntax

[RobertDober]

Now:

     option :version, :integer, 42

Then

     option :version, :integer, default: 42

---

Now:

     option :version, :integer, nil, :required

Then

     option :version, :integer, required: true

---

Now

   option :elixir, :boolean, :group, :language
   option :erlang, :boolean, :group, :language
   group_option :all, for: :language

Then

  option_group :languages do
    option :elixir # boolean is implicit
    option :erlang
    # a set them all option named `--all-languages` will be created automatically
  end