active memory maps. This removes the need to change the memory
map from common to attribute every time a packet is sent/received.
This increases performance and decreases cpu load (ping times on
slow machines improve by about 1.5ms).
Move out the old common memory/attrbiute memory hack functions to a
new header file to tidy up the main code. I want to keep them available
for a while.
The prior version in the tree was repo-copied from Duncan Barclay's
cvs tree.
Also add $FreeBSD$
Submitted by: Duncan Barclay
Committed-via: raylan link with two webgear cards.
