We just don't have the memory to be a real TLS client on the 8266. Put
that in a big box and point at it from the http and mqtt modules; others
may also wish to give reference.
* mqtt:connect() secure parameter should be boolean
Continue to honor the old 0/1 values, but make them undocumented and add
a deprecation warning to the code and docs. Eventually, this should go
away.
* mqtt: rip out deprecated autoreconnect
* mqtt: expose all the callbacks via :on