Added resumable loading, along with signal handling.

This version can store state after receiving SIGINT.
This is achieved by polling FIFO read state;

U2F_Register_APDU.hpp

@@ -11,6 +11,6 @@ struct U2F_Register_APDU : U2F_Msg_CMD
 	public:
 		U2F_Register_APDU(const U2F_Msg_CMD &msg, const std::vector<uint8_t> &data);
 
-		void respond();
+		void respond(const uint32_t channelID) const override;
 };