Minor cleanup on servers, make logs better
Minor performance improvements

Force inline in pqueue.c (probably makes 0 real difference).  Also,
don't validate outgoing utf8 in protocol.c (will definitely make a
difference for large utf8 outgoing messages).
Use MONOTONIC_CLOCK on systems that support it

Use clock_gettime and MONOTONIC_CLOCK in event.c if the system supports
it.
test_client.c: tweaks, fix commandline opts
client: remove unused state variable
server: add heartbeats and handshake timeout

Servers can now specify a heartbeat interval, a heartbeat ttl and a max
handshake timeout.