mmem: Prevent duplicate init of mmem

This could seriously corrupt data if mmem_init was called again after
someone called mmem_alloc.
[avr] Removed usage of deprecated MCUSR

Since avr-libc 1.8.0 MCUSR is marked as poison as it was replaced by the
correct name MCUCSR.
Thus code still using the old MCUSR name does not compile anymore.

This commit replaces usages of former MCUSR by its new name MCUCSR and
modifies the alias fallback accordingly.
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>
core/net/rime/ipolite: stop ctimer and reset queuebuf pointer when canceling old send

Ipolite is used by netflood and route-discovery modules among others. If a route request is yet to be re-broadcasted and a local route discovery is started (interval == 0), the previous queuebuf used is freed but ctimer and queuebuf pointer is left unchanged. This causes corrupt route requests to be sent, invalid routing tables to be formed, memcmp() on NULL pointer on receive, and other undefined behavior.

Signed-off-by: Oskar Nordquist <oskar.nordquist@crlsweden.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.
Added missing memb_free in queuebuf.c
Fix deallocation in queuebuf.c, case where QUEUEBUF_STATS is set
Remove unnecessary list_remove in ctimer.c (list_add automatically removes first)
struct queuebuf_data: swap len with data to make sure data is 32-bit aligned
struct frame802154_t: make sure dest_addr and src_addr are aligned
frame802154: move inclusion of linkaddr.h from .h to .c file
[doc] fixed some minor typos
[doc] added base doxygen file for apps and cpu directory to doc/
[doc] moved doxygen parts from core/net/simple-udp.c to corresponding
header file
[doc] updated settings manager documentation
[doc] Various fixes for doxygen grouping etc.
[core/net/rime] Doxygen fixes
[core/net/mac] Doxygen: Added frame802154 to net group
[doc] added faulty esb and msp430 references
[core/net/rime] Avoid equal group titles in same group