requested change: remove special cases

This removes the special cases of imprint and index. Those did not have
weight defined, while all other had. From this on, all pages without
weight defined will not been shown in the menu, not only those two.

Author: knarrff

_includes/navbar.html

@@ -31,7 +31,7 @@
                 {% assign pg = site.pages | sort: "weight" %}
                 {% for node in pg %}
                     <!-- Neglect imprint.html and index.html in either language -->
-                    {% unless node.path contains "imprint" or node.path contains "index" or node.weight <= 0 %}
+                    {% unless node.weight == nul or node.weight <= 0 %}
                         <!-- Set variable "node_conf2019" if node links to a conference page -->
                         {% assign node_conf2019 = false %}
                         {% if node.url contains "/conf2019/" %}