server: switch to int64 for stream offsets

We need to check if the ring code can safely handle int32 wraparound.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
server: use the persistent stream reader in the main connection loop

We only acknowledge input packets once we've committed all the results.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>