Added session key to ServerConnection

src/client/client.h

@@ -20,6 +20,7 @@ typedef struct ServerConnection {
     Socket content_socket;
     br_rsa_public_key server_pk;
     EncryptorRSA rsa_enc;
+    Array(u8) session_key;
     EncryptorAES session_aes_enc;
     DecryptorAES session_aes_dec;
 } ServerConnection;