WaitTillDetached is a hangover from prior code.
Rename IsAwake-->WillCall. The Awake/Asleep nomenclature is a hangover from elsewhere.
Ensure FD is valid, -1 damages the stack and causes crashes.
First cut at ZSocketWatcher (finally). Akin to ZCallScheduler, it invokes callables when their associated sockets become readable.
Support for Register, Browse and Resolve.