xreader Save option

[krazykelv]

Currently the xreader menu only has a "Save a Copy..." option and no plain "Save". The only way to save to the current file I found was to exit the program where it offers 4 options include "Save" before quit.

I propose the following changes:

• Add a Save option to the File menu.
• Re-map the Ctrl - S shortcut from "Save a Copy" to "Save"
• Create a new shortcut for "Save a Copy". I suggest Ctrl - Shift - S which is what LibreOffice uses.

This change would have a few benefits:

• Much easier to save long forms in pdfs to prevent losing work on the form.
• Makes users feel at ease to know their progress can be easily saved
• Aligns the app with other office apps (LibreOffice) to provide consistency

A change of keyboard shortcut is never ideal, but I think in this case it feels justified based on the above.

If there's interest in this change, I'm happy to work on a pull request.