TODO

* call time client before all others

figure out how to have pools of buffers for ports by type

passing args to drivers and clients?
getting callbacks and args from dynamically loaded clients?
how do dynamically loaded clients (un)register ports, activate, etc.
pool based malloc for rt client-local mem allocation

TO THINK ABOUT:

multiple port buffer shm segments (i.e. dynamically
         increase the total number of ports in the system)

