Merge pull request #74 from BirdseyeSoftware/development

Add missing monitor on CreateHandle variant of ChildStart in Supervisor. Thanks Tavis Rudd!
remove potential pattern match failure in favour of more helpful `die message`

initCall and unsafeInitCall in D.P.P.ManagedProcess.Internal.Types
were both vulnerable to pattern match failure when passed an
unresolvable Addressable. It is more helpful to the developer /
debugger to die with `unresolvableMessage addressable`.