Problem: generated selftest code is wrong

Fixed it.
Problem: borks if there's no grammar section defined

Solution: allow grammar to default to ''
Problem: generated test case did not compile

Solution: fixed errors.
Problem: need hook to configure server from server init

Solution: added engine_configure() hook
Problem: verbose messages in all services

Not good for silent services like zgossip.

Solution: user can log in server_initialize and server_terminate.
It doesn't have to be forced by the engine.
Problem: email addresses in AUTHORS harvested for spam

Solution: remove these email addresses, since authors are reachable
via their Git commit history.
Problem: need to broadcast to ALL clients

Solution: broadcast off server, optionally filtering on client
Problem: need default log prefix for clients

Solution: use zactor_new argument as string for all clients in a
given server. This can be overridden in any client method for any
given client.
Merge pull request #66 from hintjens/master

Bunch of changes to server engine generator