RouterAddress:

- Add new constructor
 - Add add getHost() and deepEquals()
 - Compare host string, not IP, in equals()

SSU:
 - Remove all _external* fields; use _currentAddresses in super
 - Big rework of externalAddressReceived(), rebuildExternalAddress(),
   needsRebuild(), and replaceAddress() for multiple addresses and IPv6
 - Add caching in UDPAddress
 - More IPv6 flavors of utility methods
 - Remove two-art replaceAddress()

core/java/src/net/i2p/data/RouterAddress.java

@@ -54,6 +54,17 @@ public class RouterAddress extends DataStructureImpl {
         _options = new OrderedProperties();
     }
 
+    /**
+     *  For efficiency when created by a Transport.
+     *  @param options not copied; do not reuse or modify
+     *  @since IPv6
+     */
+    public RouterAddress(String style, OrderedProperties options, int cost) {
+        _transportStyle = style;
+        _options = options;
+        _cost = cost;
+    }
+
     /**
      * Retrieve the weighted cost of this address, relative to other methods of
      * contacting this router.  The value 0 means free and 255 means really expensive.
@@ -171,7 +182,7 @@ public class RouterAddress extends DataStructureImpl {
         if (_ip != null)
             return _ip;
         byte[] rv = null;
-        String host = _options.getProperty(PROP_HOST);
+        String host = getHost();
         if (host != null) {
             rv = Addresses.getIP(host);
             if (rv != null &&
@@ -183,6 +194,17 @@ public class RouterAddress extends DataStructureImpl {
         return rv;
     }
     
+    /**
+     *  Convenience, same as getOption("host").
+     *  Does no parsing, so faster than getIP().
+     *
+     *  @return host string or null
+     *  @since IPv6
+     */
+    public String getHost() {
+        return _options.getProperty(PROP_HOST);
+    }
+    
     /**
      *  Caching version of Integer.parseInt(getOption("port"))
      *  Caches valid ports 1-65535 only.
@@ -239,7 +261,7 @@ public class RouterAddress extends DataStructureImpl {
     }
     
     /**
-     * Transport, IP, and port only.
+     * Transport, host, and port only.
      * Never look at cost or other properties.
      */
     @Override
@@ -249,12 +271,24 @@ public class RouterAddress extends DataStructureImpl {
         RouterAddress addr = (RouterAddress) object;
         return
                getPort() == addr.getPort() &&
-               DataHelper.eq(getIP(), addr.getIP()) &&
+               DataHelper.eq(getHost(), addr.getHost()) &&
                DataHelper.eq(_transportStyle, addr._transportStyle);
                //DataHelper.eq(_options, addr._options) &&
                //DataHelper.eq(_expiration, addr._expiration);
     }
     
+    /**
+     *  Everything, including Transport, host, port, options, and cost
+     *  @param addr may be null
+     *  @since IPv6
+     */
+    public boolean deepEquals(RouterAddress addr) {
+        return
+               equals(addr) &&
+               _cost == addr._cost &&
+               _options.equals(addr._options);
+    }
+    
     /**
      * Just use a few items for speed (expiration is always null).
      * Never look at cost or other properties.