[mod] improve handling of the hotkeys

- KeyboardEvent: keyCode property is depricated, replaced by key property [2]

- the check for ifDetailOpened is not necessary, because the hotkeys are not
  only applicable to image-results, by example:

   `!goi !go !scc hello`

- Key bindings like h for help are to be used in general (not only in vim-mode)

[1] https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode
[2] https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/static/themes/simple/src/js/main/results.js

@@ -74,10 +74,6 @@
       searxng.scrollPageToSelected();
     }
 
-    searxng.isDetailOpened = function () {
-      return d.getElementById('results').classList.contains('image-detail-open');
-    }
-
     searxng.closeDetail = function (e) {
       d.getElementById('results').classList.remove('image-detail-open');
       searxng.scrollPageToSelected();