Fine-grained options for ReSpeller

I kind of like the new ReSpeller feature, but I feel it needs much more fine grained control over where it takes effect in order to be useful, yet not annoying. :)

In my case, I'd like to see it enabled at code & comment level, but not in strings (any strings, not just verbatim ones). Similarly, per-file-type control would also be welcome, so that I could disable it entirely for JSON files, etc.

Maybe add a few more options in this vein for next release? :)

Otherwise, great job!