enable --inder for certtool --dh-info

certtool --dh-info is unable to read DER-encoded DH parameters without
this patch.
enable --outder for certtool --dh-info

"certool --dh-info --outder" produces PEM-encoded output without this
patch.
in gnutls_x509_privkey_generate() allow specifying an explicit curve.
doc update
reindented code
stribute the autogen'erated files as .bak and enable them only if local libopts is being used.
improved indentation in headers.
doc update
Improvements in the detection of function prototypes to account for the new indentation.
simplified gnutls_pkcs11_copy_x509_crt()
test before copy
Improvements in PKCS #11 support.

Added gnutls_pkcs11_obj_export3 and gnutls_pkcs11_get_raw_issuer.
The latter function allows to obtain the issuer of a certificate stored in a token.

While traversing tokens, use the URL provided by the user, to avoid looking
for objects in unrelated tokens.
Added export-chain option to p11tool
When importing a certificate PKCS #11 try to import the whole chain.

This affects gnutls_certificate_set_x509_key_file*().
doc update
updated
Allow getting the PIN from the GNUTLS_PKCS11_PIN environment variable.
simplified checks
Avoid infinite loops with self-signed certificates present in the chain
Added test suite for PKCS #11 cards (not executed automatically).