add functions and keys to change search type and case

[maw]

I'm not wild about the implementation but the functionality is convenient.

Also, I feel like there ought to be a word that's like "toggle" but to move among three or more mutually exclusive options. But if it exists I can't for the life of me remember what it is.

[bestlem]

The word you are after is cycle.

An Emacs example is used by org as per https://orgmode.org/manual/Global-and-local-cycling.html

[maw]

The word you are after is cycle.

It is indeed! :smile: It finally occurred to me about half an hour after I submitted this pull request.

[Wilfred]

Thanks! :)