SusiDNS: Fix adding to empty address book

by doing form processing even if book is empty.
Do all form processing before displays so the
displays reflect any form add/delete.
Broken in 0.9.50 when form processing call was moved.
Hide replace and add alternate buttons if book is empty.
Ref: https://www.reddit.com/r/i2p/comments/wu7nac/how_do_i_add_to_the_private_address_book/

router/java/src/net/i2p/router/RouterVersion.java

@@ -18,7 +18,7 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Git";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 5;
+    public final static long BUILD = 6;
 
     /** for example "-test" */
     public final static String EXTRA = "";