improve logging

[k9ert]

• We now have a --tracerpc switch which will dump each and every call to core/elements in the debug-logs like e.g.:

[  DEBUG] in             rpc: call(wallet/specter/mytrezor_2   ) payload:[{'method': 'listtransactions', 'params': ['*', 1000, 0, True], 'jsonrpc': '2.0', 'id': 0}]
[  DEBUG] in             rpc: call(wallet/specter/mytrezor_2   ) payload:[]
[  DEBUG] in             rpc: call(wallet/specter/mytrezor_2   ) payload:[{'method': 'getwalletinfo', 'params': [], 'jsonrpc': '2.0', 'id': 0}]

• We have a different logging-scheme for dev than for production (no timestamps and a bit more structure for dev)

[stepansnigirev]

Looks good to me, except exit() thing above