Merge branch '203-remove-tor-binaries' into 'master'

Remove Tor binaries from repo. #203

This patch removes the Tor binaries from the repo - the binaries will be downloaded at build time and verified using SHA-256 hashes included in the repo.

After this branch has been merged I plan to reduce the size of the repo by rewriting the commit history to delete the Tor binaries (and various other cruft that used to live in the repo, such as fonts).

After the history has been rewritten, everyone will need to delete their local repo and clone a fresh copy. I'll send out some warnings beforehand.

See merge request !147