Tor multithreaded crypto

[George Kadianakis]

Hey,

I won't be playing with this for the next few days because of exams
and whatnot so I felt like throwing some minor progress I've done in
here.

Like I said in #tor-dev, treat it as pseudocode. Nothing is set in
stone and I'm just organizing everything in code to better understand
Nick's design. 

Behold! You can find a git diff here:
http://people.cs.unipi.gr/asn/multicrypto.patch

Like I said (and you will notice it right away, really) it's just
blueprints in code.
If any poor soul actually wants to open the file and look what's
inside, comments are more than welcome!

Thank you.