Improve logic in network.py's set_parameters()
Improve logic in network.py's set_parameters()

1) For new proxy or protocol, restart the network and default to
   the requested server.
2) Otherwise if we aren't using the requested server, switch to it
3) Otherwise choose a random server if the requested server is
   stale and auto_connect is True

As switch_to_interface() now has another user, move the logic
there whereby we close the old interface in order to terminate
subscriptions, in order to have it in one place.

lbryio/lbryum,aasiutin/electrum,fireduck64/electrum,wakiyamap/electrum-mona,procrasti/electrum,neocogent/electrum,cryptapus/electrum,vertcoin/electrum-vtc,asfin/electrum,vialectrum/vialectrum,wakiyamap/electrum-mona,cryptapus/electrum,argentumproject/electrum-arg,cryptapus/electrum-uno,spesmilo/electrum,asfin/electrum,protonn/Electrum-Cash,pknight007/electrum-vtc,asfin/electrum,spesmilo/electrum,fujicoin/electrum-fjc,molecular/electrum,vertcoin/electrum-vtc,FairCoinTeam/electrum-fair,dashpay/electrum-dash,protonn/Electrum-Cash,molecular/electrum,digitalbitbox/electrum,cryptapus/electrum-myr,cryptapus/electrum-uno,dabura667/electrum,romanz/electrum,dabura667/electrum,dabura667/electrum,molecular/electrum,fyookball/electrum,FairCoinTeam/electrum-fair,pknight007/electrum-vtc,imrehg/electrum,fireduck64/electrum,romanz/electrum,fyookball/electrum,wakiyamap/electrum-mona,argentumproject/electrum-arg,imrehg/electrum,pooler/electrum-ltc,vertcoin/electrum-vtc,fujicoin/electrum-fjc,aasiutin/electrum,pooler/electrum-ltc,aasiutin/electrum,argentumproject/electrum-arg,pknight007/electrum-vtc,FairCoinTeam/electrum-fair,pknight007/electrum-vtc,dashpay/electrum-dash,aasiutin/electrum,imrehg/electrum,cryptapus/electrum-uno,pooler/electrum-ltc,fujicoin/electrum-fjc,digitalbitbox/electrum,FairCoinTeam/electrum-fair,cryptapus/electrum,fyookball/electrum,lbryio/lbryum,fireduck64/electrum,vialectrum/vialectrum,neocogent/electrum,fireduck64/electrum,procrasti/electrum,kyuupichan/electrum,dashpay/electrum-dash,pooler/electrum-ltc,romanz/electrum,molecular/electrum,dashpay/electrum-dash,cryptapus/electrum-myr,digitalbitbox/electrum,argentumproject/electrum-arg,spesmilo/electrum,kyuupichan/electrum,protonn/Electrum-Cash,spesmilo/electrum,imrehg/electrum,vialectrum/vialectrum,cryptapus/electrum-uno,digitalbitbox/electrum,procrasti/electrum,protonn/Electrum-Cash,kyuupichan/electrum,dabura667/electrum,neocogent/electrum,wakiyamap/electrum-mona,procrasti/electrum,cryptapus/electrum-myr,vertcoin/electrum-vtc,cryptapus/electrum-myr