fix #21 Remove overloaded use of ZMQ_RCVMORE/SNDMORE with multi-buffer sequences
Resolve problem with monitor test failing

Also added purge() to socket
Fix send/receive usage consistent with previous commit's changes
Rename purge -> flush

Consistent with CZMQ naming
Fix formatting
Insert .5sec delay before tearing down ios in monitor test

Hopefully addresses spurious failures in CI test runs
Lengthen delay in monitor test to 1sec

Windows CI build still seems to fail with .5sec
Merge pull request #49 from rodgert/master

fix #21 Remove overloaded use of ZMQ_RCVMORE/SNDMORE with multi-buffer sequences