net: TCP thin-stream latency-improving modifications

This is a series of patches enabling non-intrusive, dynamically triggered modifications that improve retransmission latencies for thin streams.

The patch set was modified according to the feedback received.

Major changes:
-Renamed central variables, sysctls and ioctls. -Removed redundant allocations.
-Added documentation in ip-sysctl.txt. -Added tcp thin-stream info in new file: tcp-thin.txt.

Cheers,
Andreas Petlund