Issue #931250: Providing options to configure the root element of XML request documents generated by XML Formatter. This is implemented in a backwards-compatible way, so existing deployments shouldn't be affected.

Fixed bug that made it impossible to do a request alter because it was assumed that $this->request_alter was an object implementing alterRequest(). It now works with any callable.

by fago: Change to use drupal_json_encode(), breaking change

#732308 by Jeffrey04, Hugo Wetterberg: Added missing function parameters while doing interpreting response
by SimmeLj: Extended base formatter to allow sending of data as a form
by Hugo Wetterberg: Fixed logic error that caused the accept-header to be set only when a request with a request body was made
by voxpelli: Now throws exception when JSON decoding fails and not just when the PHP decoding fails
by voxpelli: Made it possible to specify a realm as well as to send parameters when using the OAuth authentication header

Made it possible to specify a realm as well as to send parameters when using the oauth authentication header.

Fixed logic error that caused the accept-header to be set only when a request with a request body was made.

Separated out the curl-specific stuff into RestClientCurlDelegate, which leverages the also new delegate system.

Fixed the autoload hook and renamed RestClient.php to RestClient.inc.

Reintroduced some encapsulation in the RestClientRequest and reworked the flow a bit so that it would still work with rest_client_oauth.

Removed unnecessary dependency on OAuth common if no authentication is used. And a method for getting the last curl error