default to copy=True in ZMQStream.send
default to copy=True in ZMQStream.send

which used copy=False by default.

It doesn't make sense to use different defaults than Socket.send,
and non-copying sends can cause problems on shutdown without
manually terminating the context in Python 3.

ref: #173

yyt030/pyzmq,ArvinPan/pyzmq,dash-dash/pyzmq,Mustard-Systems-Ltd/pyzmq,Mustard-Systems-Ltd/pyzmq,dash-dash/pyzmq,caidongyun/pyzmq,ArvinPan/pyzmq,dash-dash/pyzmq,swn1/pyzmq,yyt030/pyzmq,swn1/pyzmq,yyt030/pyzmq,swn1/pyzmq,ArvinPan/pyzmq,caidongyun/pyzmq,caidongyun/pyzmq,Mustard-Systems-Ltd/pyzmq