Convert topic filter to regexes

Unused for now, but will come in handy for designing a nice subscription
API with callbacks.
Performance optimization

No need for backtracking. Haven't benchmarked if it's actually faster.
Subscription support, no documentation yet.
Get rid of IO::Select

This use of select() is so simple, having the module is *more* LoC :-)
Drop connection before it's too late.
Let tick return something meaningful-ish
Update documentation for the new subscription feature
UTF-8-decode incoming publish, document unicode stuff, doc tweak.
Command line utility "mqtt-simple".
Bump version to 1.10