Renamed GlobalLink to MessageMembrane.
Renamed "listen"  to syncOnInDemandAvailable, now that we don't have a "link, listen" pun.
Renamed "behavior internal objects" to "links" in the TODO comments.
Added makeLinkedSigPair, and made several linkFoo() utilities for patching them together into a network. These one-way signals will be much easier to work with than the two-way membranes.