Ensure that PATH_INFO and REQUEST_URI are following the CGI specifications:
- PATH_INFO is percent decoded but still utf-8 encoded,
  this is available via WGI.path_info and WSF_REQUEST.utf_8_path_info.
- Added WSF_REQUEST.percent_encoded_path_info
- and WSF_REQUEST.path_info remains the unicode value for PATH_INFO

Added cgi_variables: WGI_REQUEST_CGI_VARIABLES to have a simple and quick view on CGI variables
Added execution_variables to be able to iterate on execution variables.
Added PERCENT_ENCODER.percent_decoded_utf_8_string
Improved the WSF_DEBUG_HANDLER to provide more information thanks to WSF_DEBUG_INFORMATION object.
Improved the debug example, so that it outputs more information.