NAVWEB and WEBCAL: some minor corrections (#980)

* NAVWEB: set unused media to False by default

Fixes #11496

* Navweb: Center correctly the map in the web page

* Webcal: Dropmenu doesn't work if only one year.

* Navweb: Add notes to updates and delete empty rows

* Navweb: some code cleanup.

* Navweb: remove unused variable

* Narweb: references enhancement on place pages.

* Navweb: convert the years in gregorian cal.

* Narweb: remove unused argument

* Narweb: really solves the pyICU problem

* WEBCAL: missing death symbol

data/css/narrative-maps.css

@@ -31,7 +31,7 @@ body#FamilyMap {
     margin-left: 10px;
     margin-right: 10px;
     border: solid 4px #000;
-    margin: 0px auto;
+    margin: 20px auto;
     width: 800px;
     height: 400px;
     max-width: 90%;