Rename "Dispatcher"

[empijei]

Currently "Dispatcher" conveys the meaning of something that moves the responses to the output, that dispatches Write calls to response writers.

What it does not convey is that it has to be secure, to be a "guard" against vulnerabilities.

We should find a better name for this very important type that adds that meaning before we release this.

I would propose something like "Guard" or "CheckWriter" or "GateKeeper".

[kele]

SafeResponseWriter?