[xmlsec] New xmlsec 1.2.15 release

[Aleksey Sanin]

The new XML Security Library 1.2.15 release available at
the usual place:

    http://www.aleksey.com/xmlsec/download.html

This release includes the following changes:

* xmlsec-mscrypto: Added HMAC with MD5, SHA1, SHA256/384/512;
   RSA with MD5, SHA256/384/512 support.

* xmlsec-mscrypto: Converted to Unicode (the non-Unicode
   builds are still available as compile time option).

* xmlsec-nss: Added MD5 and SHA256/384/512 support for digest,
   HMAC and RSA (the new minimum required version for NSS
   library is 3.9).

* xmlsec-gnutls: Added SHA256/384/512 for digest and HMAC;
   MD5 and RIPEMD160 digests support (the new minimum required
   version for GnuTLS library is 2.8.0).

* Several critical bug fixes and code cleanups.

Thanks to everyone for the contribution, patches and bug reports!

Aleksey Sanin