Refactoring del terminale virtuale

A new virtual terminal has been created.

Now, when the output it set, the connection with the terminal it is always active and it is not possible to close or open the terminal manually without a DISPLY/TERM command.

If the user wants to hide the terminal, then he should minimize it.

If the terminal is closed, then the user has to raise a confirmation in order to make sure that there is not any unwanted disconnection.