Do not assume transfer-encoding: chunked as default on requests.

If users do not send transfer-encoding or content-length headers, then I
will not add any additional. Content-Length: 0 is assumed if there aren't
other headers and chunked encoding is rare.

src/http.js

@@ -359,16 +359,17 @@ node.http.Client = function (port, host) {
       header += "Connection: keep-alive\r\n";
     }
 
-    if (sent_content_length_header == false && sent_transfer_encoding_header == false) {
-      header += "Transfer-Encoding: chunked\r\n";
-      chunked_encoding = true;
-    }
     header += CRLF;
      
     var output = [];
     send(output, header);
 
     this.sendBody = function (chunk, encoding) {
+      if (sent_content_length_header == false && chunked_encoding == false) {
+        throw "Content-Length header (or Transfer-Encoding:chunked) not set";
+        return;
+      }
+
       if (chunked_encoding) {
         send(output, chunk.length.toString(16));
         send(output, CRLF);

website/api.html

@@ -750,6 +750,12 @@ req.finish(function (res) {
         by Node. Returns a <code>ClientRequest</code> object.
       </p>
 
+      <p>
+        Do remember to include the <code>Content-Length</code> header if you
+        plan on sending a body. If you plan on streaming the body, perhaps
+        set <code>Transfer-Encoding: chunked</code>.
+      </p>
+
       <p>
         Important: the request is not complete. This method only sends
         the header of the request. One needs to call