r21278: The main goal of this was to get rid of the NetInBuffer / set_InBuffer. But it

r21278: The main goal of this was to get rid of the NetInBuffer / set_InBuffer. But it
turns out that this patch actually speeds up the async writes considerably.

I tested writing 100.000 times 65535 bytes with the allowed 10 ops in
parallel. Without this patch it took about 32 seconds on my dual-core 1.6GHz
laptop. With this patch it dropped to about 26 seconds. I can only explain it
by better cache locality, NewInBuffer allocates more than 128k, so we jump
around in memory more.

Jeremy, please check!

Volker
(This used to be commit 452d51bc6fd41771b9c41ba6391664513d7cf2cd)