Extends the default Range#include? to support range comparisons.
(1..5).include?(1..5) # => true
(1..5).include?(2..3) # => true
(1..5).include?(2..6) # => false
The native Range#include? behavior is untouched.
("a".."f").include?("c") # => true
(5..9).include?(11) # => false