Cargo: Cleanup unused dependencies, enable some build optimizations
Tor: Arti doesn't seem to work on macOS
Even a bare Arti+Hyper request doesn't seem to work, so it's
probably not something to do with Gupax. A lot of issues only
seem to popup in a VM (OpenGL, TLS) even though on bare metal
Gupax runs fine, so Tor might work fine on real macOS but I don't
have real macOS to test it. VM macOS can't create a circuit, so,
disable by default and add a warning that it's unstable.
P2Pool: Let selected_index start at 0, and only +1 when printing
to the user, this makes the overflow math when adding/deleting a
lot more simple because selected_index will match the actual index
of the node vector
