A keyListener was created and minor changes in AboutAction

It was added a KeyListener to the text area of the main window
WorkFile interface altered and WorkFileV1 updated

added new important methods: getFile(), setName(), setContent(),
setFile()
Added the functionality to OpenAction and new functions to Dwriter

Now it is possible to open a new file using the application. It checks
if the current file has been altered so it will ask the user if he wants
to save.
The new functions of the Dwriter class are:
loadContent(), yesNoCancelMessage(), saveAsFile(), saveFile(),
saveActiveWorkFile(), getWorkFiles(), addNewWorkFiles()
Added reload method to Frame and minor changes

the new reload function will load the data of the activeWorkFile object
and sets a new title to the window and the content to the main textArea.
Created a custom JFileChooser for the application

for now, its file selection mode is for files only