Generalize Utils#slugify for any scripts

It replaces any non alphanumeric glyphs by an hyphen.

lib/jekyll/utils.rb

@@ -113,7 +113,7 @@ module Jekyll
       unless string.nil?
         string \
           # Replace each non-alphanumeric character sequence with a hyphen
-          .gsub(/[^a-z0-9]+/i, '-') \
+          .gsub(/[^[:alnum:]]+/i, '-') \
           # Remove leading/trailing hyphen
           .gsub(/^\-|\-$/i, '') \
           # Downcase it

test/test_utils.rb

@@ -120,6 +120,7 @@ class TestUtils < Test::Unit::TestCase
 
     should "drop trailing punctuation" do
       assert_equal "so-what-is-jekyll-exactly", Utils.slugify("So what is Jekyll, exactly?")
+      assert_equal "كيف-حالك", Utils.slugify("كيف حالك؟")
     end
 
     should "ignore hyphens" do
@@ -134,6 +135,10 @@ class TestUtils < Test::Unit::TestCase
       assert_equal "customizing-git-git-hooks", Utils.slugify("Customizing Git - Git Hooks")
     end
 
+    should "replace punctuation in any scripts by hyphens" do
+      assert_equal "5時-6時-三-一四", Utils.slugify("5時〜6時 三・一四")
+    end
+
     should "not modify the original string" do
       title = "Quick-start guide"
       Utils.slugify(title)