Implemented partial ACKs to handle logstash shutdown gracefully.
Tuned thread priorities.
Tuned ACK message format.
Set ZeroMQ LINGER to 10s to ensure ACKs are delivered to clients.
Move context.terminate to teardown. Seems like a good idea.
Handle OutOfMemory when opening and reading file.
Pass OutOfMemory exception to top exception handler before doing an abort
so that the SystemExit exception that is raised by abort is not caught by
higher handlers.
adjust shutdown behavior
Merge branch 'develop'