memberships: modal for errors (#133)

* unpolished version of error modal rendering

* rework of html files. template implemented

* new html files

* minor fixes.

* minor fixes

* title changes
diff --git a/core/auth/memberships/memberships-tmpl/user.html b/core/auth/memberships/memberships-tmpl/user.html
new file mode 100644
index 0000000..53a89be
--- /dev/null
+++ b/core/auth/memberships/memberships-tmpl/user.html
@@ -0,0 +1,54 @@
+{{ define "title" }}
+    User - {{ .CurrentUser }}
+{{ end }}
+{{- define "content" -}}
+    <h1>User: {{ .CurrentUser }}</h1>
+    {{ if .LoggedInUserPage }}
+    <form action="/create-group" method="post">
+        <label for="group-name">Group Name:</label>
+        <input type="text" id="group-name" name="group-name" required>
+        <label for="description">Group Description:</label>
+        <input type="text" id="description" name="description">
+        <button type="submit">Create Group</button>
+    </form>
+    {{ end }}
+    <h4>Owner</h4>
+    <table>
+        <tr>
+            <th>Name</th>
+            <th>Description</th>
+        </tr>
+        {{- range .OwnerGroups -}}
+        <tr>
+            <td><a href="/group/{{ .Name }}">{{ .Name }}</a></td>
+            <td>{{ .Description }}</td>
+        </tr>
+        {{- end -}}
+    </table>
+    <h4>Member</h4>
+    <table>
+        <tr>
+            <th>Name</th>
+            <th>Description</th>
+        </tr>
+        {{- range .MembershipGroups -}}
+        <tr>
+            <td><a href="/group/{{ .Name }}">{{ .Name }}</a></td>
+            <td>{{ .Description }}</td>
+        </tr>
+        {{- end -}}
+    </table>
+    <h4>Transitive Groups</h4>
+    <table>
+        <tr>
+            <th>Name</th>
+            <th>Description</th>
+        </tr>
+        {{- range .TransitiveGroups -}}
+        <tr>
+            <td><a href="/group/{{ .Name }}">{{ .Name }}</a></td>
+            <td>{{ .Description }}</td>
+        </tr>
+        {{- end -}}
+    </table>
+{{- end }}