review design of GW_RESPONSE to hide the output, and remove the header attribute
added script_url in REQUEST to help the user build url relative to script_name
+ cosmetic
So this is really more flexible this way, and much easier to write application supporting CGI, FCGI, Nino and so on .. as demonstrated in hello_world
This is a first version, more will come later, mainly migrating from Eiffel Web Reloaded to this Eiffel Web Framework project.