[docs] Library Reference, asyncore module, basic echo server

[scaven]

Hello
Could you please make a little change in Library Reference, asyncore module
http://docs.python.org/library/asyncore.html#asyncore-example-basic-echo-server

change
         self.send(data)

to
         if data!='': self.send(data)

this will prevent error messages about sending to a closed client socket
thx