SAM: Cherrypick from patch in ticket #1318:

- Add SIGNATURE_TYPE support to GENERATE and CREATE
   - Don't NPE checking dest+privkeys
   - Simplify HELLO checking
   - Don't require two params in HELLO message
   - Make MIN parameter optional too
   - Version checking fixes
   - Bump version to 3.1, only visible if requested
   - Cleanups, javadocs

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 = 9;
+    public final static long BUILD = 10;
 
     /** for example "-test" */
     public final static String EXTRA = "";