nfacct: Fix DBG() format string for uint64_t
netlink-test: Fix printf format string for uint64_t
netlink-test: Use open coded message creation instead of struct

struct nfacctmsg did not adhere to the alignment requirements and
was broken for 32bit machines.
doc: Update Session overview

Explain how application identification works and how per application
routing and statistics is implemented.
inet: Fix IPCMv6 checksum calculation

The router advertisement message has more data to send so we
need to tweak checksum calculation to check the extra bytes.
inet: Add function to get the link local address attached to an interface
inet: Return errors correctly when setting multicast options
inet: Enhance debug print usefullness
gdhcp: Print debug information about sent requests
gdhcp: Ignore server DUID missing error

This way client DUID is at least added to the message even if
server DUID is missing. The DUID might be missing if server did
not send it. This is normally an error but here the upper layer
needs to figure that out.
gdhcp: Pretty print DUID to the debug log
gdhcp: IPv6 prefix delegation support

Add support functions that are needed by DHCPv6 code for prefix
delegation.
gdhcp: Read only sub-option amount of data

If the address option was not the last one, then we could read
too much data when parsing the sub-option. This caused uninitialized
memory read error in valgrind.
gdhcp: Get server DUID if we do not know it yet

Prefix delegation renew support needs server DUID but we might not
yet have it.
gdhcp: Print more error information if DHCPv6 message send failed

sendmsg() has been seen failing with EADDRNOTAVAIL. Unfortunately
no better information is seen in log so it is a mystery what happened.
Print some extra info when this happens.
inet: Add function to send ICMPv6 router advertisement message
inet: Add functions to receive ICMPv6 router solicitation messages
ipconfig: Save and load delegated IPv6 prefixes
dhcpv6: Initial IPv6 prefix delegation support

This patch adds start and stop prefix delegation functions.
The  __connman_dhcpv6_start_pd() is used to initiated the prefix
delegation. It will send the solicitation or rebind message to
the server depending on if we have old prefixes saved.
The __connman_dhcpv6_stop_pd() clears the prefix delegation data
and stops the delegation.
The normal DHCPv6 and prefix delegation can be going on at the
same time as they are used for different purposes. The PD is only
used if we are acting as a router i.e., when tethering.
dhcpv6: Add prefix delegation renew support

Renew the delegation from uplink DHCPv6 server when running out of
prefix lease time.