Version 1.2

+ added file impl with basic support for card emulation (now only from
memory).
+ reworked Blockwise impl using IOCP.
+ commands.h now contains available command codes for generic reader.
+ refactored relationship between reader and impl: reader now performs
most of generic checks for received packet.
Card reset implementation + minor changes.

Implemented card_reset function that performs reset of card state
currently in reader field and also makes sure it's the same card
as before.

Bytestaffing function definitions now reside in protocol.h
instead of every implementation file.