* Make it possible to extract more useful data from the certificate
* Also get the OpenSSL error message when a certificate can't be
validated. Send it to the verification failure callback so it can be
shown to the user.
* Instead of creating an OpenSSL context ofor each socket, use a global
one and initialize it lazily when the first SecureSocket is created
* Load the certificates from our certificate list so SSL certificates
sent by servers can be validated.
* Add a callback for signalling that certificate validation failed, the
default implementation proceeds with the connection anyway (to keep the
old behavior).
* Introduce BCertificate class, that provides some information about a
certificate. Currently it's only used by the callback mentionned above,
but it will be possible to get the leaf certificate for the connection
after it's established.
Review of the API and implementation is welcome, before I start making
use of this in HttpRequest and WebKit to allow the user to accept new
certificates.
