Smart case support

[rauchg]

It might be interesting to use vi-style smart case. If you include at least one uppercase letter, the search becomes case sensitive.

Also implemented by spot:

https://github.com/rauchg/spot#smart-case

[sindresorhus]

Interesting. How do you force it to be only lowercase? Or is that not a common use-case?

[pirate]

Might be better to not try and be "too smart", and just have a cli argument like -s for 'case-sensitive'.

For example, ag (the silver searcher) is case-insensitive by default, but you can force case sensitivity with -s or --case-sensitive.