Add Option url.open_base_url

when set to true, invoking a searchengine shortcut without argument
opens the baseurl of that searchengine instead of DEFAULT searchengine

qutebrowser/config/configdata.yml

@@ -1445,6 +1445,12 @@ url.incdec_segments:
   desc: URL segments where `:navigate increment/decrement` will search for
     a number.
 
+url.open_base_url:
+  type: Bool
+  default: false
+  desc: Invoking `:open {shortcut}` (without argument), where {shortcut} is a search engine shortcut
+    will open the base url of the shortcut instead of using the default search engine.
+
 url.searchengines:
   default:
     DEFAULT: https://duckduckgo.com/?q={}

qutebrowser/utils/urlutils.py

@@ -102,6 +102,13 @@ def _get_search_url(txt):
         engine = 'DEFAULT'
     template = config.val.url.searchengines[engine]
     url = qurl_from_user_input(template.format(urllib.parse.quote(term)))
+
+    if config.val.url.open_base_url:
+        try:
+            search_url = urllib.parse.urlparse(config.val.url.searchengines[term])
+            url = QUrl('{}://{}'.format(search_url.scheme, search_url.netloc))
+        except KeyError:
+            pass
     qtutils.ensure_valid(url)
     return url