Allow customizing the highlight color

[alecb-stripe]

Feature request: Allow customizing the color of the highlight when showing "found" instances.

I use hyper-snazzy, and the highlight color works well enough when I'm actually highlighting text, but it's not distinguishing enough to draw my eyes to the found text in the middle of a bunch of output. If it's possible for this plugin to use a different highlight color (or otherwise do more to draw your eyes to the found text), that would help a lot.