Declutter logs and split actor into different goroutines

Regarding logs i have removed ```OnTxAccepted``` notifications since ```btcwallet``` already informs us about successful transactions, triggered TXST not to show information since we don't care about them, and changed ```OnBlockConnected``` to be output by thousands until the miner starts mining new blocks.

Regarding the actor communication, i have split each task in a separate goroutine, which makes things a bit faster (so transactions can proceed faster too) than before when we were using a single goroutine working on each channel.

I have also made some idiomatic fixes and removed the closing of ```upstream``` when calling ```addInterruptHandler```, which i think is unnecessary.