Ipv6: Rebase on V1, add socket stack, config

The socket stack is untested.
Merge remote-tracking branch 'refs/remotes/avsm/master'

Conflicts:
	_oasis
	lib/META
	setup.ml
	unix/ipv6_socket.ml
	unix/tcpv6_socket.ml
	unix/tcpv6_socket.mli
	unix/udpv6_socket.ml
Fix configuaration for the direct stack

Only IPv4 can be configured so far.  Ipv6 needs to be configured
"manually".
oasis: make tcp depend on ipv6
Ipv6: Remove pause before starting
Rename STACK => NETSTACK