Resolve host names.
Benchmark the Ptr operations.

These are only minorly faster, but that isn't the point.  The point is
that users don't need to create a bytestring, which can be horribly slow
(think: cereal), and can instead poke into stack-allocated buffers.
That's the savings.
Remove "Unsafe" version of connection.

It had yet to show any possible use case, which would have to be from
performance improvements that didn't appear to exist.
Remove dead code.
Remove old existentials.
Continue removing MVar/IORef type variables.  Should have done a build
test.