Add Alt-U shortcut to clear search highlight

[tiymat]

Adds the Alt-U keybinding from less to clear highlights on searched text.

[walles]

How did you test this? You can run ./moar.sh with the same command line parameters as moar to try your changes locally.

Your PR did not work for me when I tested it.

Also, from less --help:

  ESC-u                Undo (toggle) search highlighting.
  ESC-U                Clear search highlighting.

An Alt-combination might have worked, but Esc (same as ESC, short for "Escape") is used for exiting moar (and a lot of other things on different systems), so that's not something I'll be supporting as a prefix.

[tiymat]

How did you test this? [...] Your PR did not work for me when I tested it.

I tested it using the moar binary I built (with go build) after making my changes. I just tried with moar.sh and it also worked. My exact commands were

1. ./moar.sh ./go.mod
2. /req
3. ENTER
4. ALT-u

and the highlighted occurrences of req cease to be highlighted. The same keystrokes work in less for me. I don't have any config for moar or less. Maybe it's something keyboard related. Out of curiosity, I tried in a different shell and different terminal and it continued to work.

My reason for this PR is that when reading a large file I will commonly use a search to find a specific part of the file. However, after I've found the part of the file I want, I no longer need the text to be highlighted, and find it distracting.

[tiymat]

If you'd prefer it to use a different Alt-combination I could certainly make that change. Otherwise, if you aren't interested in this shortcut being in moar, I can close the PR.

Either way, thanks for your work developing and maintaining moar :)

[walles]

I'm missing something here.

Adds the Alt-U keybinding from less to clear highlights on searched text.

In less, Alt-U does nothing.

Is this PR about adding less' ESC-U key combination to moar?

Or is this PR about adding Alt-U support to moar, which less does not have?

What am I missing here?

Alt key combos might work, but I'm skeptical about ESC.

[tiymat]

I'm still very surprised that the key combination doesn't do anything for you. I've tried on both Arch and Ubuntu, and I've switched keyboard layouts from US English to a couple of European ones (German and Swedish) and it behaved the same every time.

I can see in less that pressing Alt-u results in the \033u command being processed, which it maps to ESC-u. I might try to dig further into the code that gets that command this weekend if I get a chance. I guess I'll close this PR though, as it seems my setup is behaving differently than others' so I can't properly test my PR.

[walles]

I'm still very surprised that the key combination doesn't do anything for you.

Which key combination? Alt-U or ESC-u?

There is no connection between the two.

pressing Alt-u results in the \033u command being processed, which it maps to ESC-u.

When you say that Alt-u "maps to ESC-u", can you clarify this?

Alt and ESC are completely unrelated.

When you say that one "maps to" the other, what exactly do you mean by that?

Sorry if I'm being dense here, but I'm super confused.

[walles]

Or put in another way, which of these two are you after?

1. Press and release ESC, then press and release u
2. Press and hold Alt, then press and release u, then release Alt