clustermq 0.8.95

• We are now using ZeroMQ via Rcpp in preparation for v0.9 (#151)
• New multiprocess backend via callr instead of forking (#142, #197)
• Sending data on sockets is now blocking to avoid excess memory usage (#161)
• multicore, multiprocess schedulers now support logging (#169)
• New option clustermq.host can specify host IP or network interface name (#170)
• Template filling will now raise error for missing keys (#174, #198)
• Workers failing with large common data is improved (fixed?) (#146, #179, #191)
• Local connections are now routed via 127.0.0.1 instead of localhost (#192)
• Submit messages are different between local, multicore and HPC (#196)
• Functions exported by foreach now have their environment stripped (#200)
• Deprecation of log_worker=T/F argument is rescinded