Fix visability issues.

U2F_Version_APDU.hpp

@@ -19,7 +19,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #pragma once
 #include "U2F_Msg_CMD.hpp"
 
-struct U2F_Version_APDU : U2F_Msg_CMD {
+class U2F_Version_APDU : public U2F_Msg_CMD {
 public:
 	U2F_Version_APDU(const U2F_Msg_CMD& msg, const std::vector<uint8_t>& data);
 	void respond(const uint32_t channelID) const override;