Have a Tor package that can run Flash safely

I'm using this as the new catch-all ticket for letting users somehow use Flash with Tor.

Currently we're working on three directions in parallel:

A) Wrap the Adobe Flash plugin in policies so it can't harm us too much (legacy/trac#7008 (moved))

B) Support Mozilla's plans to integrate a Javascript flash thingie into Firefox (legacy/trac#7500 (moved))

C) Put the entire browser, Flash, and related stuff in a VM that can't talk to the outside world unsafely (legacy/trac#7681 (closed))