Fix #3747, #3749

getipaddr() now returns an IP object or throws an error if no external
interfaces are available. Furthermore this also always sets bind-to to
127.0.0.1 for local workers.
Revert part of my pkg2 WIP that accidentally made it into the last commit
Move bind-to to back to launch-procs since addprocs can launch non-local commands
improve inlining of promote_type. fixes #3734