Make Pike compatible with chunked transfer encoding

Imported from https://youtrack.roxen.com/issue/PIKE-234

Reported by Eduardo Rodes Pastor erodes@roxen.com

At the moment, Pike does not allow chunked encoding. The current workaround is adding this line to HTTP.Protocols.Server.Request.pike:568:

radd("Transfer-Encoding: ", m->transfer_encoding);

This must be approved (or changed) and pushed to the Pike source code, since the new IDS proxy version does not work without it.