[FEATURE] Highlight links

[pinbraerts]

I want to visibly distinguish the links, so that I can know beforehand if they can be gx'ed.

Here are my thoughts about this feature:

1. opt-in setting (false by default)
2. define some highlight group (I couldn't find the standard)
3. check every handler lazily on some action: visible buffer lines on cursor move and bufopen
4. cache results
5. invalidate cache on edit

Inspiration:
https://github.com/catgoose/nvim-colorizer.lua

[chrishrb]

hm.. i think it would be overwhelming because you can gx anything - even words. maybe for all except of words this would be cool..