Add ability to abort from Vim exit code

[sukima]

In many cases where Vim is used as an intermediate step in a series of steps it is helpful to abort when the user explicitly exits vim with a non-zero exit code.

What that means in this project is that if the user who is editing the buffer decides that he/she does NOT wish to overwrite the clipboard (maybe they realized they have something important) they would quit Vim with :cq instead of the normal ways. This means they can write the file all they want and it will not be copied to the clipboard if they use the :cq command.

Granted the utility of this is debatable making this change optional.