Improved query and form data encoding (based on a very early version of the general URI percent-encoding rules).

- now correct encoding of space by '%20' in path segment, and '+' in query parameters.
Unify and fixed query parameters handling for libcurl and net implementation.
Fixed file uploading (various issue in libcurl, and net implementation).
Fixed form multipart encoding by using correctly the boundary.
Updated autotest cases.
Code cleaning.

library/text/encoder/src/x_www_form_url_encoder.e

@@ -0,0 +1,47 @@
+note
+	description: "Summary description for {X_WWW_FORM_URL_ENCODER}."
+	author: ""
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	X_WWW_FORM_URL_ENCODER
+
+inherit
+	URL_ENCODER
+		redefine
+			append_percent_encoded_ascii_character_code_to
+		end
+
+feature {NONE} -- Implementation: character encoding
+
+	append_percent_encoded_ascii_character_code_to (a_code: NATURAL_32; a_result: STRING_GENERAL)
+			-- <Precursor>
+			-- Note: space is encoded with '+' for x-www-form-urlencoding.
+		do
+			inspect a_code
+			when
+				32 -- 32 ' '
+			then
+				a_result.append_code (43) -- 43 '+'
+			when
+				33, 39,		-- ! '
+				40, 41, 42 -- ( ) *
+			then
+				a_result.append_code (a_code) -- Keep slash
+			else
+				Precursor (a_code, a_result)
+			end
+		end
+
+note
+	copyright: "Copyright (c) 2011-2017, Eiffel Software and others"
+	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
+	source: "[
+			Eiffel Software
+			5949 Hollister Ave., Goleta, CA 93117 USA
+			Telephone 805-685-1006, Fax 805-685-6869
+			Website http://www.eiffel.com
+			Customer support http://support.eiffel.com
+		]"
+end