Non-breaking space in menu link name
Use this in your theme so menu items can be processed as html 

use Drupal\Core\Render\Markup;

/**
 * Implements hook_preprocess_HOOK()
 * processes 1 nested level of menu items
 */
function THEMENAME_preprocess_menu(&amp;$vars){  
  if($vars['menu_name'] == "main"){
    foreach($vars['items'] as &amp;$link){
      $link['title'] = Markup::create($link['title']);
      foreach($link['below'] as &amp;$nestedlink){
        $nestedlink['title'] = Markup::create($nestedlink['title']);
      }
    }
  }
}


Alternatively you can use css to make regular white space not wrap

.menu li a {
    white-space: nowrap;
}


Of course you have to adjust css for your particular menu class