Alert before quit electron with unsaved changes

[murilopolese]

• Electron will not close it's window until the UI confirms it can be closed
• The UI will look for open files with unsaved changes.
• A new file will never be considered "changed", only files that have been saved will be counted as unsaved changes.

[ubidefeo]

A bit of an edge case, but maybe not that edge :)

When I launch the editor the "new file" is pre-filled and its tab's dirty indicator (*) is already present.
Of course the file has not been saved yet, but I am still able to add my own code, run and test things out.
If I close the editor or the tab in question I do not get prompted to save, and I see this as lacking in this feature

[murilopolese]

@ubidefeo

This is a design decision.

• I think if you haven't done anything on the app and click exit, you should exit without a warning that there are unsaved changes.
• If you haven't saved the file, you shouldn't be prompted to save it before you exit. New files (that are not saved) work like temporary files. No save, no persistence.
• Since we are not doing "content diff" if you press space and delete the space (on an existing file) the system will think there are unsaved changes on that file.

[ubidefeo]

LGTM