Update cmd.go

Golang does not require break

core/cmd.go

@@ -57,19 +57,14 @@ func (cm *Cmd) parseInternalCmd() {
 	switch cmd {
 		case InternalCmdHelp:
 			cm.printHelpMessage()
-			break
 		case InternalCmdEnv:
 			fmt.Println("External plug-in path : "+cm.plugHandle.dir)
-			break
 		case InternalCmdList:
 			cm.plugHandle.PrintList()
-			break
 		case InternalCmdVer:
 			fmt.Println(cxt.Version)
-			break
 		case InternalDevice:
 			cm.printDevice()
-			break
 	}
 	os.Exit(1)
 }