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: prefix csum properly and add documentation
Merge pull request #2019 from authmillenon/cleanup-net_help

net_help: Cleanup
examples/riot_and_cpp: cleanup in Makefile

removed some deprecated comments about C++
Merge pull request #2028 from haukepetersen/fix_riotandcpp_makefile

examples/riot_and_cpp: cleanup in Makefile
cpu/sam3x8e: made _kill(_r) syscalls weak
boards: enabled C++ for arduino-due and udoo
Merge pull request #2031 from haukepetersen/fix_sam3x_cpp

ACK then ;)
and go!