Add uint16_t key to Hashtable, and make Salsa20 zero its keyspace on destruction.

node/Hashtable.hpp

@@ -382,7 +382,10 @@ private:
 	}
 	static inline unsigned long _hc(const uint32_t i)
 	{
-		// In the uint32_t case we use a simple multiplier for hashing to ensure coverage
+		return ((unsigned long)i * (unsigned long)0x9e3779b1);
+	}
+	static inline unsigned long _hc(const uint16_t i)
+	{
 		return ((unsigned long)i * (unsigned long)0x9e3779b1);
 	}