Remove Version#to_a alias

Exposing this as "to_a" was a mistake, versions are not arrays and it
causes incorrect behavior when splatted or using Kernel#Array(). Use the
more correct name "tokens" instead.

Library/Homebrew/requirements/python_dependency.rb

@@ -24,10 +24,10 @@ class PythonInstalled < Requirement
 
   class PythonVersion < Version
     def major
-      to_a[0].to_s.to_i  # Python's major.minor are always ints.
+      tokens[0].to_s.to_i  # Python's major.minor are always ints.
     end
     def minor
-      to_a[1].to_s.to_i
+      tokens[1].to_s.to_i
     end
   end
 

Library/Homebrew/version.rb

@@ -184,7 +184,6 @@ class Version
   def tokens
     @tokens ||= tokenize
   end
-  alias_method :to_a, :tokens
 
   def tokenize
     @version.scan(