Feature request — colored non-breaking spaces

Hi,

I really love the non-breaking space highlighting functionnality on Emacs:

The on-breaking space (U+00A0 or more commonly known as   in HTML) is really important in typography and I often use the Unicode character in HTML source code instead of the   escape code. The benefit is that a b is much more readable than a b, and the drawback is that it’s hard to differenciate a regular space from a non-breaking space without any special highlighting.

So, it would be awesome if micro could slightly highlight U+00A0. The simple Emacs’ colored underline looks good enough to me. Is it possible to implement this functionnality as a plugin?

(Of course, I can edit every single syntax file I use and copy-paste the same rule for those non-breaking spaces, but this looks like a rather ugly fix to me. I really prefer highlighting non-breaking spaces globally with one single setting, as Emacs does.)

Thanks for all the nice work you’ve done so far 🙂

No files, tests, or entry points are named. Start by locating micro's global highlighting and plugin-related code, then trace how syntax highlighting is applied across buffers. Done means U+00A0 characters receive consistent visual highlighting globally without editing each syntax file, with coverage for the behavior added where appropriate.