Added IPv6 routing support to SDN-IP, and integrated it with BGP:
 * The routing entries as received from BGP can be either IPv4 or IPv6
 * The CLI prints the IPv4 and IPv6 routes
 * The BGP peering is still over IPv4, so configuration-wise the IPv6
   routes from the eBGP peers have to be configured to use the IPv4 peering.
 * The integration/testing with the IPv6 Network Discovery Protocol is not
   done yet.
 * The integration/testing with IPv6 intents is not done yet.

Also:
 * Moved nested class BgpSessionManager.BgpRouteSelector out of the
   BgpSessionManager class.
 * Code cleanup.

Change-Id: I9f2dbe4395a72d353bbf215a8a14b01b53c3423f
diff --git a/apps/sdnip/src/main/java/org/onosproject/sdnip/SdnIp.java b/apps/sdnip/src/main/java/org/onosproject/sdnip/SdnIp.java
index 066500b..2b95129 100644
--- a/apps/sdnip/src/main/java/org/onosproject/sdnip/SdnIp.java
+++ b/apps/sdnip/src/main/java/org/onosproject/sdnip/SdnIp.java
@@ -164,13 +164,23 @@
     }
 
     @Override
-    public Collection<BgpRouteEntry> getBgpRoutes() {
-        return bgpSessionManager.getBgpRoutes();
+    public Collection<BgpRouteEntry> getBgpRoutes4() {
+        return bgpSessionManager.getBgpRoutes4();
     }
 
     @Override
-    public Collection<RouteEntry> getRoutes() {
-        return router.getRoutes();
+    public Collection<BgpRouteEntry> getBgpRoutes6() {
+        return bgpSessionManager.getBgpRoutes6();
+    }
+
+    @Override
+    public Collection<RouteEntry> getRoutes4() {
+        return router.getRoutes4();
+    }
+
+    @Override
+    public Collection<RouteEntry> getRoutes6() {
+        return router.getRoutes6();
     }
 
     @Override