Refactored keccak interface

- Allow calculating keccak hash in steps
- Only allow 32 and 200 byte final hashes

src/p2pool.cpp

@@ -1032,7 +1032,7 @@ void p2pool::parse_get_miner_data_rpc(const char* data, size_t size)
 	}
 
 	hash h;
-	keccak(reinterpret_cast<const uint8_t*>(data), static_cast<int>(size), h.h, HASH_SIZE);
+	keccak(reinterpret_cast<const uint8_t*>(data), static_cast<int>(size), h.h);
 	if (h == m_getMinerDataHash) {
 		LOGWARN(4, "Received a duplicate get_miner_data RPC response, ignoring it");
 		return;