Gui saves custom client id and loglevel

- gui NewWindow takes SimpleClientIdentity as argument
- gui NewWindow takes ethutil.ConfigManager as argument to manage flag persistence
- gui now saves loglevel and custom client id via config.Save
- rename custom client id methods consistently also in wallet.qml
- clientIdentifier now set in main wrappers
- version handled within wrapper
- modify InitConfig now returning *ethutil.ConfigManager (passed to gui)

ethereal/assets/qml/wallet.qml

@@ -248,9 +248,9 @@ ApplicationWindow {
 						text: "Client ID"
 					}
 					TextField {
-						text: eth.clientId()
+						text: eth.getCustomIdentifier()
 						onTextChanged: {
-							eth.changeClientId(text)
+							eth.setCustomIdentifier(text)
 						}
 					}
 				}