Bug fixes and renaming (again)

We can now handle node failures and rolling restarts under fairly high
load.

Fixed memory leaks (we don’t leak memory under failure conditions)

I when back to the previous naming convention of proper case for the
opaque pointer types. I’m like likely not going to go back this time.
:) The other way (“<type>_t”) is a bit cleaner for a C API, but doesn’t
match the conventions of the implementation at all.