Some small cleanups.

TODO: remove old todos that have been done.
Updated TODO.
Some work done on the onion announce part.
A bit of work done on the onion part.
Some work on the onion part done.
Tests added and some fixes for the onion part.
onion_announce seems to be working perfectly.

Stuff added and fixed.
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.