Restore old signal escalation semantics by adding
JOBS_REQUEST_GRACEFUL_REMOVAL which defaults to false.  Also allow
remove_kill_sig to define the kill signal and prefer it to kill_sig if
both are defined. #3470
Changed JOBS_REQUEST_GRACEFUL_REMOVAL -> GRACEFULLY_REMOVE_JOBS and it is
now a default for whether to gracefully remove jobs.  #3470
Added protection against LookupBool changing semantics. #3470
Merge branch 'master-orig-signal-escalation-semantics'
Version history for custom signal semantics fix. #3470