MERGED: @holimans changes

MERGED: @piwi changes
MERGED: @marshmellows changes.

I'm not even gonna try write up all that stuff..

ADD: changed some commands inside the "Hf 14a sim" on deviceside.
ADD: @mobeius "two nonce" version for mfkey32.   It is also inside the "hf 14a sim" with the "x" parameter.

common/usb_cdc.h

@@ -41,6 +41,7 @@ void usb_disable();
 void usb_enable();
 bool usb_check();
 bool usb_poll();
+bool usb_poll_validate_length();
 uint32_t usb_read(byte_t* data, size_t len);
 uint32_t usb_write(const byte_t* data, const size_t len);