Add netns.sh, a script for /etc/netns/X→/etc/ support
Add netns.sh, a script for /etc/netns/X→/etc/ support

Add a shell script wrapper for `ip netns add/delete' which sets up an
overlayfs mount merging /etc/netns/X with /etc/ in a mount namespace
stored in /var/run/mountns. nsdo will then setns() to /var/run/mountns/X
if it exists, making applications run by nsdo respect /etc/netns/
(netns-specific files in /etc/).

ausbin/nsdo,ausbin/nsdo