WordsCounter: isEmpty and clear are added.
MainWindow: clear wordsCounter_ on start.
FileParser: isRunning and started are added.
FileParser: emit finished.
MainWindow: rewrite startWork.
MainWindow: updateProgress every 100 msecs.
MainWindow: calculateEta is added.
MainWindow: Worked time is added.
MainWindow: set enabled saveResult button.
WordsCounter: saveResult is added.
MainWindow: saveResult is added.
FileParser: emit finished if file not open.
MainWindow: show messages.
FileParser: small codefix.