Overzealous autocorrect for single-quoted strings

[whitequark]

The following string shouldn't be re-quoted: "foo \\\n bar".

This is also not in a need for correction :) %w(' ")

In fact parser's builtin rewrite safety mechanism should have prevented that... dunno why you decided to turn it off.

[bbatsov]

Since all cops are rewriters, changes they make have to be written back immediate or they'd be written over by the next rewriter. The current code is flawed since the source buffer is updated, but the ast and the tokes are not. I should think of some better solution, but haven't had much time to work on that feature lately.

[bbatsov]

Fixed.