mmem: Prevent duplicate init of mmem

This could seriously corrupt data if mmem_init was called again after
someone called mmem_alloc.
[avr] added missing mcu parameter to ASFLAGS in order to enable assembler compilation
atmega128rfa1: Fix the default build error

Fixing from http://sourceforge.net/p/contiki/mailman/message/32494852/

Signed-off-by: Weichuan Yan <yan.weichuan@gmail.com>
Adding a scan-build command

scan-build http://clang-analyzer.llvm.org/scan-build.html is a clang
based tool designed to provide static analysis over C code files.
packetbuf: Added function "packetbuf_holds_broadcast()" for checking whether the current packet is a
broadcast
packetbuf: Use packetbuf_holds_broadcast() all-over
Do not trigger global repair when forwarding error is detected
Rank error packet should not be forwarded
Drop forwarding error packet and send back DAO to originating parent
Force NUD on default routers
Seedeye platform: add the explicit list of modules
Changed sorting order of routing list (optimization).
ContikiMAC: Added missing length function to contikimac-framer.c
ContikiMAC: Retain original copyright
ContikiMAC: Default to contikimac_framer when using Rime over ContikiMAC
examples/webserver-ipv6: Add UIP_CONF_TCP=1 to DEFINES.

TCP is mandatory for this HTTP server.

Fixes builds for platforms which have TCP turned off by default (mulle)

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
examples/ipv6/rpl-border-router: Add -DUIP_CONF_TCP=1 to CFLAGS

The example used to rely on the default value being set to 1 which
caused build failures on platforms which have a default UIP_CONF_TCP=0

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
avr: fix divide when CLOCK_SECOND is not a power of two
Decreasing annoyance from debug messages.
Merge pull request #878 from jlusticky/avr-clock-fix

avr: fix divide when CLOCK_SECOND is not a power of two