CardOS 5 driver for OpenSC

This change builds upon existing CardOS 4 code to implement a CardOS 5
driver for OpenSC. CardOS 4 and 5 differ substantially.  The code
currently supports on-card generation and storage of RSA keys up to 2048
bits in modulus.

Support for 4096-bit RSA keys is still deffective. I'm currently
investigating why.