restructure flashproxy source tree

The source tree has quite a messy structure that makes it hard to write a coherent install script, e.g. for debian packaging. I propose something like the following:

Top-level

renamed: doc/design.txt -> design.txt

client

renamed: Makefile -> client/Makefile

renamed: doc/flashproxy-$$ -> client/doc/flashproxy-$$

renamed: flashproxy-$$ -> client/flashproxy-$$

renamed: setup.py -> client/setup.py

renamed: torrc -> client/torrc

facilitator

renamed: doc/facilitator-howto.txt -> facilitator/doc/facilitator-howto.txt

renamed: doc/appengine-howto.txt -> facilitator/doc/appengine-howto.txt

renamed: doc/gmail-setup.txt -> facilitator/doc/gmail-setup.txt

renamed: appengine/$$ -> facilitator/appengine/$$

websocket-transport

renamed: doc/websocket-transport.txt -> websocket-transport/doc

proxy

renamed: modules/$$ -> proxy/modules/$$

/websocket-transport.txt

plus the necessary adjustments (paths etc) to make everything work again.