Remove destiny header dependency from net_help
Merge pull request #663 from authmillenon/rm-addr-conv-dep

Remove destiny header dependency from net_help
Add quadword math lib

GCC implicitly calls functions like __adddi3 to handle arithmetics on
long long.

Copied from http://ftp3.usa.openbsd.org/pub/OpenBSD/src/lib/libc/quad/
which is curtesy of the OpenBSD project (3 clause BSD license).
Add compile time checks to quad.h
Adapt quad lib to RIOT conding convention