Correct typo in CmdGenerator comment.
Correct GetWorkCmd.

The getwork RPC now only accepts a single optional parameter which, if
present, is a string containing the hex-encoded block data to solve.

Also update the tests for the new correct parameters.

ok @jcvernaleo
Allow getwork result to be a bool or JSON object.

The getwork command alters the output depending on whether or not the
optional data parameter was specified.  It is a JSON object when no data
was provided, and a boolean indicating whether a solution was found
when data was provided.
Add support for GetPeerInfoResult.
Add support for GetRawMempoolResult.
Fix missing ) in comment.
Export a couple of peer-to-peer client errors.

ok @jcvernaleo
recieve->receive