IsoApplet: clear memory after prkey import.

Private key import via plain APDUs is dangerous and not recommended anyway, but clearing the apdu buffer does not hurt anyone.
IsoApplet: Move the key gen debug info to the right places
IsoApplet: Align comments with spaces instead of tabs

Better view with tabstop=8.
sc_asn1_put_tag - support larger tags

Enhance sc_asn1_put_tag to support larger tag names and larger tags.
Prior to this, sc_asn1_put_tag did only support tags with a length of at most 127 bytes and tag names of one byte.
adjust send/receive size accoriding to card capabilities
EC key storing: make sure algorithm params are available

When trying to import EC keys onto the card with pkcs15-init, the
params.ec of sc_pkcs15init_prkeyargs or pubkeyargs had not been
initialized. This commit fixes that by reading the curve name from the
EVP_KEY and initializing the parameters.

Also, in sc_pkcs15_encode_pubkey_as_spki, this commit adds code that
tries to construct the EC algorithm params from the key itself. This
prevents a NULL parameter in the SPKI/ASN1 encoding.
EC key storing: use the correct parameters

When trying to import EC keys onto a card with pkcs15-init, the
params.ec of sc_pkcs15init_prkeyargs or pubkeyargs had not been
initialized. In this case, use (or point to) the parameters of the
actual key contained in the same struct.
pkcs15-lib: prkey_bits - use private key field length

sc_pkcs15init_keybits can behave erroneously with certain EC keys. It basically strips leading most significant zero-bits. EC keys (privateD) can, however, have valid zeros at the beginning which legitimately count to the field length.
So, one can NOT calculate reliable key lengths only by looking at the privateD component of the private key. You have to look at the field length specified in the parameters.