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