Merge pull request #2555 from authmillenon/ng_icmpv6/feat/initial

Makefile.dep

sys/Makefile

sys/include/net/ng_icmpv6.h

sys/include/net/ng_icmpv6/echo.h

sys/include/net/ng_icmpv6/error.h

sys/include/net/ng_icmpv6/types.h

sys/net/crosslayer/ng_netreg/ng_netreg.c

sys/net/network_layer/ng_icmpv6/Makefile

sys/net/network_layer/ng_icmpv6/echo/Makefile

sys/net/network_layer/ng_icmpv6/echo/ng_icmpv6_echo.c

sys/net/network_layer/ng_icmpv6/ng_icmpv6.c

sys/net/network_layer/ng_ipv6/ng_ipv6.c

sys/shell/commands/Makefile

sys/shell/commands/sc_icmpv6_echo.c

sys/shell/commands/shell_commands.c