Transport Plugins: Update (GSoC 2012)

Hello,

This is an update on the first stage of my project. I have been
working out the details regarding modifications in the core to
simplify the implementation of the transport plugins. This refactoring
stage will involve some minor modifications and some major ones. These
are based on the discussions on #freenet and #freenet-chat. However I
would like to avoid doing changes that would bring about major
differences in the way things function at present.

I have planned to finish refactoring by May 21 (official coding begins
for GSoC). I intend to do that in 3 stages. I have also simultaneously
discussed the entire implementation of transport plugins here. I will
review the feedback and this report, to evaluate what constitutes the
refactoring. After those changes are made I can work on implementing
the needed core level changes, which mostly involve design for
streams.

1) Cryptography and Node

This will involve mainly the classes NodeCrypto and Node. I intend to
make NodeCrypto function purely for keys and not do any network
related task. Presently it also handles binding to the port, selection
of ports for Darknet mode and Opennet mode.
I am considering moving these portions to TransportManager and
PortManager classes.

TransportManager - A registry of registered transports with other
information. Initially I ll dump the refactor changes of UDP into it.
Later on, once UDP is ready as a plugin, along with TCP, it ll be a