mosquitto 0.5

- No longer store QoS=0 messages for disconnected clients that do not have
  clean start set.
- Rename msg_timeout option to retry_interval for better rsmb compatibility.
- Change persistence behaviour. The database is now stored in memory even if
  persistence is enabled. It is written to disk when mosquitto exits and also at
  periodic intervals as defined by the new autosave_interval option.
- The writing of the persistence database may be forced by sending mosquitto
  the SIGUSR1 signal.
- Clients that do not send CONNECT as their first command are now
  disconnected.
- Boolean configuration values may now be specified with true/false as well as
  1/0.
- Log message on CONNECT with invalid protocol or protocol version.
- Default sqlite3-pcre path on Linux is now /usr/lib/sqlite3/pcre.so to match
  future sqlite3-pcre packages.
- Add mosquitto_sub and mosquitto_pub, simple clients for subscribe/publish.
- Add man pages for clients.
- Add general man page on mqtt.
- Root privileges are now dropped only after attempting to write a pid file
  (if configured). This means that the pid file can be written to /var/run/
  directly and should fix bug #523183.