implemented storing edit as new version, impelemented loading of arbitrary versions of wiki page

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

web/src/main/resources/web/css/default.css

@@ -69,6 +69,13 @@ nav {
   border-radius: 6px;
 }
 
+.warn {
+    background: yellow;
+    color: black;
+    padding: 5px;
+    border-radius: 6px;
+}
+
 fieldset[tabindex="0"]{
     max-height: 55px;
     overflow: hidden;
@@ -369,4 +376,13 @@ table{
     position: absolute;
     right: 0;
     bottom: 0;
+}
+
+.version > a{
+    padding: 5px;
+}
+
+.version a.selected{
+    border: 1px solid orange;
+    border-radius: 5px;
 }