Fix: flux calculation from area-propotional value instead of normal value. (#654)

* bioms shouldn't be masked or the style selection box is useless

* fix: misleading comment

* Fix: calculating absolute flux from precipitation normal-value.

* Fix: River automatic rerender on regeneration.

Co-authored-by: Mészáros Gergely <monk@geotronic.hu>

index.css

@@ -190,6 +190,12 @@ a {
 #cults {
   stroke-linejoin: round;
   fill-rule: evenodd;
+}
+
+#statesBody,
+#provincesBody,
+#relig,
+#cults {
   mask: url(#land);
 }