Merge net branch into master

Main changes:

- IP stack documentation enhancements.
- IPv4 and IPv6 packet handling refactoring.
- net_buf verbosity and documentation fixes.
- Default RX stack size increased to 1500 bytes.
- Context net_buf pool is enabled by default for TCP and 6Lo.
- Atmel SAM Ethernet driver fixes.
- RPL mesh routing fixes.
- IPv6 HBH option unknown sub-option fix.
- TCP retry timer fix.

----------------------------------------------------------------
Jukka Rissanen (4):
      doc: Enhance IP stack overview documentation
      net: Move IPv6 packet handling from net_core.c to ipv6.c
      net: Move IPv4 packet handling from net_core.c to ipv4.c
      net: icmpv6: Print received packet type as string

Luiz Augusto von Dentz (5):
      net: buf: Generate periodic warnings for allocation that takes too long
      net: buf: Reduce verbosity of net_buf_get
      net: buf: Add CONFIG_NET_BUF_WARN_ALLOC_INTERVAL
      net: ip: Increase RX stack size
      net: Enable context buffer pool in case TCP and 6LO are enabled

Paul Sokolovsky (2):
      net: Elaborate output of net_nbuf_print_frags() to be more useful.
      net: buf: Document that after data, structure may contain "user_data"

Piotr Mienkowski (2):
      drivers: eth_sam_gmac: remove possible null pointer dereference
      drivers: eth_sam_gmac: Fix initialization order

Ravi kumar Veeramally (11):
      net: rpl: Add support for DAO retransmissions
      net: rpl: Move net_route_lookup to proper place
      net: nbr: Fix miss calculation of nbr size
      net: if: Fix missing submission of router lifetime timer
      net: route: Fix retrieving route nexthop
      net: route: Update IPv6 packet routing mechanism
      net: event: Add events for ROUTE ADD and DEL
      net: rpl: Refactor net_rpl_update_header function
      net: rpl: Refactor few rpl functions
      net: rpl: Return valid verdict
      net: shell: Fix crash when retrieving remaining reachable time

Tomasz Bursztyka (2):
      net/arp: Return relevant verdict if the ARP packet was consumed
      net/core: Fix wrong parameter usage for check_unknown_option()

june li (1):
      net: tcp: Start retry timer when queueing data

 doc/subsystems/networking/overview.rst            | 114 ++++--
 drivers/ethernet/eth_sam_gmac.c                   |  89 ++---
 include/net/buf.h                                 |   7 +
 include/net/net_event.h                           |   8 +
 samples/net/echo_client/prj_bt.conf               |   2 -
 samples/net/echo_client/prj_qemu_x86.conf         |   2 -
 samples/net/echo_server/prj_bt.conf               |   2 -
 samples/net/echo_server/prj_qemu_x86.conf         |   2 -
 samples/net/echo_server/prj_sam_e70_xplained.conf |   1 -
 subsys/net/Kconfig                                |  12 +
 subsys/net/buf.c                                  |  15 +-
 subsys/net/ip/Kconfig                             |   1 +
 subsys/net/ip/Kconfig.rpl                         |  12 +-
 subsys/net/ip/Kconfig.stack                       |   2 +-
 subsys/net/ip/icmpv6.c                            |  32 ++
 subsys/net/ip/icmpv6.h                            |   2 +
 subsys/net/ip/ipv4.c                              |  76 ++++
 subsys/net/ip/ipv6.c                              | 349 ++++++++++++++++++
 subsys/net/ip/l2/arp.c                            |   4 +-
 subsys/net/ip/nbr.c                               |   3 +-
 subsys/net/ip/nbuf.c                              |  20 +-
 subsys/net/ip/net_core.c                          | 424 +---------------------
 subsys/net/ip/net_if.c                            |   2 +
 subsys/net/ip/net_private.h                       |   2 +
 subsys/net/ip/net_shell.c                         |   4 +
 subsys/net/ip/route.c                             |  43 ++-
 subsys/net/ip/route.h                             |   8 +-
 subsys/net/ip/rpl.c                               | 280 +++++++-------
 subsys/net/ip/rpl.h                               |   8 +
 subsys/net/ip/tcp.c                               |   6 +
 30 files changed, 871 insertions(+), 661 deletions(-)

Change-Id: I2000fdc0847d4c8953c1a16883ea46af13dfd179
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>