Added shell of onion_client.c
Fixed problem in onion_announce.c

Added a way to know if a announce response is valid.
Putting the sendback outside the encrypted part of the response.

It's more useful this way.
Some work done on the client part.
updated TODO.
Removed useless line.
Some work on onion_client done.
Some work done on onion_client
Some work done in onion_client.
Added functions to add/remove friends in onion_client.

Added a tiny optimization to net_crypto.
Onion data packets can now be handled in onion_client.

oniondata_registerhandler(...) can be used to register different packet
types to handle them and send_onion_data(...) can be used to send these
packets.
Some packet handling code added to onion_client.
onion_client almost done.
Wrote random_path function.

Added onion_client to the build system.
describe configuration of libsodium path

after failing the installation with described error, I needed some time to realize that there might be a problem with the custom path of libsodium installed by homebrew, needing manual configuration. Hope this saves some time for somebody.
Incorporated onion into Tox.

Fixed a couple of issues related to that.
Onion servers are now DHT ready.
Small performance increases.
Fixed spelling.
Fixed segfault.