Potential upgrades to Channel Access

o generalized access to abstract data
o use multicast for broadcasting and ax the repeater
o improve client API
o improve security
o name service (wildcard queries)
o PV name prefix (for all PVs)
o client access to process passive and for maximize severity
o detect name conflicts at boot time
o multi priority connections (quality of service)
o reduce protocol overhead
o compressed protocol


o If there is a beacon anomaly then this indicates that
the server is _not_ available. Perhaps we should only
reset the search timer interval when we see a beacon 
anomaly transition into a sure steady beacon.

o make certain that a monitor callback canceling itself
does not deadlock.

o the free list library does not now cause exceptions to
occur (it uses new ( nothrow )), and therefore we should
change the new handlers to be nothrow also if this is 
the design goal.

o test the library when an IOC is running low on memory.

o The new CA interface should be multi-threaded by default.
We should continue to support a single-threaded interface,
but this would should be restricted so that it always
runs with preemptive callback disable and no threads
may join in. Alternatively, the new CA interface could
be 100% preemptive multi-threaded and the old interface
could be layered on this.