Another packet type is now handled by onion.c
onion.c now handles another packet type.
Added a function to create and send a onion packet.
Fixed small issues in onion.c
Added onion.c to build system and added a test.
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