refactor cli and gui wrapper code. Details:

- all cli functions shared between ethereum and ethereal abstracted to utils/ cmd.go (should be ethcommon or shared or sth)
- simplify main() now readable stepwise
- rename main wrapper files to main.go
- rename commmand line args definition file from config.go to flags.go
- rename Do -> Start to parallel option names
- register interrupt for rpc server stop
- fix interrupt stopping js repl and ethereum
- register interrupt for mining stop
- custom config file option from command line
- debug option from command line
- loglevel option from command line
- changed ethutil.Config API
- default datadir and default config file set together with other flag defaults in wrappers
- default assetpath set together with other command line flags defaults in gui wrapper (not in ethutil.Config or ui/ui_lib)
- options precedence: default < config file < environment variables < command line

ethereal/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"github.com/ethereum/go-ethereum/ethereal/ui"
+	"github.com/ethereum/go-ethereum/utils"
+	"github.com/go-qml/qml"
+	"runtime"
+)
+
+const Debug = true
+
+func main() {
+	qml.Init(nil)
+
+	runtime.GOMAXPROCS(runtime.NumCPU())
+
+	// precedence: code-internal flag default < config file < environment variables < command line
+	Init() // parsing command line
+	utils.InitConfig(ConfigFile, Datadir, Identifier, "ETH")
+
+	utils.InitDataDir(Datadir)
+
+	utils.InitLogging(Datadir, LogFile, LogLevel, DebugFile)
+
+	ethereum := utils.NewEthereum(UseUPnP, OutboundPort, MaxPeer)
+
+	// create, import, export keys
+  utils.KeyTasks(GenAddr, ImportKey, ExportKey, NonInteractive)
+
+  if ShowGenesis {
+    utils.ShowGenesis(ethereum)
+  }
+
+	if StartRpc {
+		utils.StartRpc(ethereum, RpcPort)
+	}
+
+	utils.StartEthereum(ethereum, UseSeed)
+
+	gui := ethui.New(ethereum, logLevel)
+	gui.Start(AssetPath)
+}