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. CardOS 5
supports on-card generation and storage of RSA keys up to 4096 bits
in modulus, and ECC up to 512 bits.

With a lot of feedback and guidance from szikora@.
Support large (> 2048-bit) keys.
Add onepin bits to CardOS 4's profile.

When the onepin profile is activated, the ACL of the DF needs to be
adjusted from SOPIN to PIN.
Add brainpoolP512r1.
Set key_info->params.len for SC_ALGORITHM_EC as well.
Export sc_pkcs15init_get_pin_reference().
Support arbitrary key sizes in pkcs15_prkey_decrypt()

Allocate 'decrypted' according to the RSA key modulus length. Fixes
decription with 4096-bit keys.
Implement list_files for CardOS5 cards.