S allius/issue397 (#405)

* add Dashboards log handler to all known loggers

* add list of last 3 warnings/errors to page

* add note list to page

* create LogHandler for the dashboard

- simple memory log handler which stores the last
  64 warnings/errors for the dashboard

* render warnings/errors as note list

* add page for warnings and errors

* fix double defined build target

* add well done message if no errors in the logs

* translate page titles

* more translations

* add Notes page and table for important messages

* add unit tests

app/src/web/templates/templ_notes_list.html.j2

@@ -0,0 +1,23 @@
+{% if notes|length > 0 %}
+<div class="w3-container w3-margin-bottom">
+  <h5>{{_("Warnings and error messages")}}  </h5>
+  <ul class="w3-ul w3-card-4">
+  {% for note in notes %}
+    <li class="{% if note.level is le(30) %}w3-leftbar w3-rightbar w3-pale-blue w3-border-blue{% else %}w3-leftbar w3-rightbar w3-pale-red w3-border-red{% endif %}">
+      <span class="w3-col" style="width:150px">{{note.ctime|datetimeformat(format='short')}}</span>
+      <span class="w3-col w3-hide-small" style="width:100px">{{note.lname|e}}</span>
+      <span class="w3-rest">{{note.msg|e}}</span>
+    </li>
+  {% endfor %}
+  </ul>
+</div>
+{% elif not hide_if_empty %}
+<div class="w3-container w3-margin-bottom">
+  <div class="w3-leftbar w3-rightbar w3-pale-green w3-border-green">
+    <div class="w3-container">
+        <h2>{{_("Well done!")}}</h2>
+        <p>{{_("No warnings or errors have been logged since the last proxy start.")}}</p>
+    </div>
+  </div>
+</div>
+{% endif %}