Updated WGI specification to ease future migration to unicode support.

Use STRING_TABLE, and better interface of READABLE_STRING_GENERAL,
    this way the signature are more flexible for unicode keys.

    Note that for now, unicode environment variables are not correctly supported in WGI
    especially the value of the variables.
    Any layer on top of EWGSI suffers from the same issues.

Better exception handling

+ code cleaning

library/server/ewsgi/specification/request/wgi_request.e

@@ -88,14 +88,14 @@ feature -- Access: Input
 
 feature -- Access: CGI meta variables
 
-	meta_variable (a_name: READABLE_STRING_8): detachable READABLE_STRING_8
+	meta_variable (a_name: READABLE_STRING_GENERAL): detachable READABLE_STRING_8
 			-- Environment variable related to `a_name'
 		require
 			a_name_valid: a_name /= Void and then not a_name.is_empty
 		deferred
 		end
 
-	meta_string_variable (a_name: READABLE_STRING_8): detachable READABLE_STRING_8
+	meta_string_variable (a_name: READABLE_STRING_GENERAL): detachable READABLE_STRING_8
 			-- Environment variable related to `a_name'
 		require
 			a_name_valid: a_name /= Void and then not a_name.is_empty
@@ -105,7 +105,7 @@ feature -- Access: CGI meta variables
 			end
 		end
 
-	meta_variables: HASH_TABLE [READABLE_STRING_8, READABLE_STRING_8]
+	meta_variables: STRING_TABLE [READABLE_STRING_8]
 			-- These variables are specific to requests made with HTTP.
 			-- Interpretation of these variables may depend on the value of
 			-- SERVER_PROTOCOL.
@@ -635,7 +635,7 @@ invariant
 	path_info_identical: path_info ~ meta_string_variable ({WGI_META_NAMES}.path_info)
 
 note
-	copyright: "2011-2012, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
+	copyright: "2011-2013, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
 	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
 	source: "[
 			Eiffel Software