Made WGI_CHUNKED_INPUT_STREAM inherits from WGI_INPUT_STREAM

Merged REQUEST.input and REQUEST.chunked_input
  Now REQUEST.input handles directly the chunked transfer encoding, or the non chunked.
Kept REQUEST.is_chunked_input since it matters that Content-Length is 0 even if there are input (chunked) data.

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

@@ -77,8 +77,7 @@ feature -- Access: Input
 
 	input: WGI_INPUT_STREAM
 			-- Server input channel
-		require
-			is_not_chunked_input: not is_chunked_input
+			--| Could also be Chunked input, but this is transparent
 		deferred
 		end
 
@@ -87,13 +86,6 @@ feature -- Access: Input
 		deferred
 		end
 
-	chunked_input: detachable WGI_CHUNKED_INPUT_STREAM
-			-- Chunked server input channel
-		require
-			is_chunked_input: is_chunked_input
-		deferred
-		end
-
 feature -- Access: CGI meta variables
 
 	meta_variable (a_name: READABLE_STRING_8): detachable READABLE_STRING_8