* handled GObject subclasses registration to ensure compatibility with different versions of Gnome Shell

* added restart button to the menu

* added function to open an interactive shell

This required the introduction of a new method within the Docker module and consequently a new action for DockerMenuItem.
Consider refactoring to handle all the logic to produce the final Docker command inside the Docker module.

* minor changes to error messages, deleted typos

* applied refactoring to move Docker logic in its own module

* replaced var with const for utility functions declarations

* general refactoring, moved gnome-shell version check into utils module

* added EditorConfig file, adjusted files indentation to be consistent with the configuration

* handled errors when running interactive commands

In case of failure launching an interactive command, a second shell is opened within the terminal emulator to let the user acknowledge the error.

* added fallback to /bin/sh when bash isn't available on the container

* minor refactoring

* applied refactoring to the functions managing Docker commands

* refactored code to replace enum commands with actions; switch statements to obtain labels and commands

* replaced actions enum with a dictionary containing infos about actions

This allows to avoid the switch method for the action label and to move the isInteractive information from the command to the real action