Util: Fix corruption of cached ReusableGZIPInputStreams,

caused by calling close() from HTTPResponseOutputStream.Pusher,
but close() rendered the underlying InflaterInputStream unusable.
Broken in -15. Caused failed HTTP fetches and other flakiness.

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

@@ -18,7 +18,7 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Monotone";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 19;
+    public final static long BUILD = 20;
 
     /** for example "-test" */
     public final static String EXTRA = "-rc";