Release 0.6.12

• Limited the signature length to 65536 bytes.
• Workaround for buggy PKCS#11 C_Sign() implementation that always returns the same signature length along with CKR_BUFFER_TOO_SMALL (thx @mskalski).
• Don't stuck if wait_for_card=false and ignore the token not found error when the authentication isn't restricted to card only (either by the option card_only or by PKCS11_LOGIN_TOKEN_NAME environment variable).
• Added an example PAM configuration which uses the ignore status result.
• Added screen_savers to the example config.
• Fixes to deal with old and new OpenSSL versions.
• Various small fixes including type casts and printf() formats.