Fixed various unicode issue related to query and form parameters.

(Especially for the multipart/form-data encoding.)
Factorized code related to smart parameters computing (handling list , table, ...) in WSF_VALUE_UTILITIES.
Fixed an issue with percent_encoded_path_info computation from request_uri.
Fixed issue with cookie addition having same cookie name.
Fixed unicode support for uploaded file.
WSF_STRING is reusing WSF_PERCENT_ENCODER.
Use unicode output for WSF_DEBUG_HANDLER.
Code cleaning

library/server/wsf/extension/handler/wsf_debug_handler.e

@@ -59,6 +59,7 @@ feature -- Access
 
 			create dbg.make
 			dbg.set_is_verbose (True)
+			dbg.set_unicode_output_enabled (True)
 			dbg.append_cgi_variables_to (req, res, s)
 			dbg.append_information_to (req, res, s)