core: move NTOHL and friends into byteorder.h
sys: use byteorder.h in cbor.c
core: allow inclusion of byteorder.h in C++ code
native: add random syscalls
native: add random peripheral implementation
tests/periph_random: fix warnings, conventions
c++: `s/restrict/__restrict/`

`restrict` is not a keyword in C++, but `__restrict` is understood by
GCC-ish compilers.
Merge pull request #1984 from Kijewski/net_help-is-odd

core: move NTOHL and friends into byteorder.h
Merge pull request #2041 from LudwigOrtmann/native-random

native: peripheral random interface
Merge pull request #2042 from Kijewski/restrict

c++: `s/restrict/__restrict/`
core: ipc: introduce new messaging API
adapt to new msg_queue API
tests: sizeof_tcb: adapt to new IPC
tests: add msg_node example/test
core: remove cib

The "circular integer buffer" was only used by the old message queues.
So remove it for now.