sorted internal requires alphabetically
use require_relative
split off ProxyObject ProxyObjectInterface ProxyObjectFactory

into their own files
coverage: include specs

each process needs a separate name otherwise simplecov overwrites their
data in coverage/.resultset.json
fixed yardoc "Cannot resolve link to n from text ... {n}"
factored out MessageQueue from Connection

Salvaging the ConnectionQueue work from the multithreading branch,
see 1ad91928060dd0123b81cf58095aef981988ebca and previous commits