Feature: broadcast all transactions over Tor

[Kixunil]

Having an option to broadcast all transactions over Tor would be a very useful feature since bitcoind doesn't support it directly and some clients don't support it. Having it in the proxy would make sure no transaction leaks over clearnet.

A global proxied_tx_brodcast option would be sufficient but perhaps doing it the same way as fetch_blocks - per-user AND global is better (consistent). We should also use RPC for testing if the TX would be accepted in the mempool before actually broacasting it.

@dr-bonez how hard do you think it'd be given that some required infrastructure (getting peers) is already implemented?

[dr-bonez]

Probably would be pretty trivial. I think we already have a Tor only flag in the config though, so either we should use that, or rename it to something more clear

[Kixunil]

Good point. I believe renaming is less confusing because people could incorrectly assume that more operations are torified.