Add a TSNetAcceptNamedDescriptor(contp, char *) function to allow a protocol plugin to set a callback for accepting new connections on a socket opened by the traffic_manager (that's defined like 2345:plugin:name=myname in the server_ports configuration).
This has three advantages on opening a socket using TSNetAccept:
1) If the traffic_server crashes and restarts, new connections won't be rejected while we recover - This is the main selling point of the new API.
2) Support for all port configuration flags (Which also exists when using TSPortDescriptorAccept)
3) Allow for a single point of configuration for all ATS ports