Added backward compatiblity for CGI.escape features

Author: hsbt

lib/cgi.rb

@@ -294,5 +294,5 @@ class CGI
 require 'cgi/core'
 require 'cgi/cookie'
 require 'cgi/util'
-require 'cgi/escape'
+require 'cgi/escape' unless defined?(CGI::EscapeExt)
 CGI.autoload(:HtmlExtension, 'cgi/html')

lib/cgi/util.rb

@@ -42,3 +42,6 @@ def pretty(string, shift = "  ")
     lines.gsub(/^((?:#{Regexp::quote(shift)})*)__(?=<\/?\w)/, '\1')
   end
 end
+
+# For backward compatibility
+require 'cgi/escape' unless defined?(CGI::EscapeExt)