Flesh out the parameterize method to support non-ascii text and underscores.

activesupport/lib/active_support/inflector.rb

@@ -257,7 +257,7 @@ def demodulize(class_name_in_module)
     #   <%= link_to(@person.name, person_path %>
     #   # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>
     def parameterize(string, sep = '-')
-      string.gsub(/[^a-z0-9]+/i, sep).downcase
+      string.chars.normalize(:kd).to_s.gsub(/[^\x00-\x7F]+/, '').gsub(/[^a-z0-9_\-]+/i, sep).downcase
     end
 
     # Create the name of a table like Rails does for models to table names. This method

activesupport/test/inflector_test_cases.rb

@@ -144,7 +144,10 @@ module InflectorTestCases
 
   StringToParameterized = {
     "Donald E. Knuth"                     => "donald-e-knuth",
-    "Random text with *(bad)* characters" => "random-text-with-bad-characters"
+    "Random text with *(bad)* characters" => "random-text-with-bad-characters",
+    "Malmö"                               => "malmo",
+    "Garçons"                             => "garcons",
+    "Allow_Under_Scores"                  => "allow_under_scores"
   }
 
   UnderscoreToHuman = {