Allow nil to be passed to and from Ruby XML-RPC servers

allow_nil.rb

require 'xmlrpc/server'

def suppress_warnings
    previous_VERBOSE, $VERBOSE = $VERBOSE, nil
    yield
    $VERBOSE = previous_VERBOSE
end

suppress_warnings do
    XMLRPC::Config::ENABLE_NIL_PARSER = true
    XMLRPC::Config::ENABLE_NIL_CREATE = true
end