It would be great if thor can provide the way to couple options. #585

Hi,
This is not a bug report but a suggestion.

We sometimes need to define options that must to be tightly coupled each other to make things work.
For example, suppose there is an option :one, --one, and it needs another option :file, --file, to make things work as we expect. So in that circumstance, it would be great if thor can provide the way to couple those options as following manner.

method_option :one, :type => :boolean, :coupling => :file
method_option :file, :type => :string, :coupling => :one

# or

method_option :one, :type => :boolean, :coupling => [:file, :url] 
method_option :file, :type => :string, :coupling => :one
method_option :url, :type => :string, :coupling => :one