- 0.1.0:  Initial version: minimal API allowing to send raw commands to a smartcard.
- 0.2.0:  Added card.reconnect() and context validation.
- 0.3.0:  Now use pcsc-sys instead of my own scard ffi: better project that should now work with windows.
          Context is now provided as a Rc to the Card struct. So Context cannot be dropped while the Card obj is alive.
          Reader name reading has no hardcoded buffer len anymore.
- 0.3.1:  Better prototype for Card.send_raw_command: use &[u8] instead of &Vec<u8>.
- 0.3.2:  Change Rc<Context> to Arc<Context> because we may have to cross a thread boundary.
