cpu/nrf51822: changed ISR stack size to 512 byte
core: remove needless test in msg.c

`thread.c` initializes a thread with an empty message queue. `cib_put()`
will `return -1` for an empty CIB, so there is no need to test if
`thread->msg_array != NULL`.
cpu/stm32f1: c++: added _kill (weak) and weak attribute for _kill_r
boards/iot-lab_M3: provided c++ feature
initial support for c++ for this cpu/board
Merge pull request #2013 from Kijewski/msg-needless-test

core: remove needless test in msg.c
Merge pull request #1985 from BytesGalore/EasyCPPMixing_stm32f4discovery_support_fix

squashed, changed comment and go.
Merge pull request #2004 from dangnhat/cpp_for_iot_lab_m3

iot-lab_m3: C++ support
Merge pull request #1932 from haukepetersen/fix_nrf_isrstacksize

cpu/nrf51822: changed ISR stack size to 512 byte
net_help: remove printArrayRange()

The od module does the same, much less specialized, much more
sophisticated.
net_help: Remove IPV6_CMP_ADDR macro

Used nowhere; alternative: ipv6_addr_is_equal(), since other use-cases
(is an IPv6 address smaller than the other) are not applicable anyway.
net_help: properly prefix csum