"All rights reserved" was incorrect. The project was licensed under GPL3,
which means a lot of rights are licensed to everybody in the world, i.e.
not reserved to the "Tox Project".
It is still C code, so still compatible with C compilers as well. This
change lets us see more clearly where implicit conversions occur by
making them explicit.
bootstrap_node_packets.c was giving an error as it was being included
twice and there were no include guards, so part of it was split into
bootstrap_node_packets.h.
