ensure we check that allowing messsage expectations on nil is isolated per example
reset expectations from proxy (which is registered on space)
grammar
refactor proxy to take nil as a special case
remove nil warnings from method double
refactor state into the ProxyForNil instance
update changelog
remove now unneccesary private api
refactor ifs back into methods
Merge pull request #277 from JonRowe/fix_isolation_of_allow_message_expectations_on_nil

Fix isolation of allow_message_expectations_on_nil