SSL.sslfile: These variables are no more.

Missed this debug output when moving the version restrictions.
SSL: Protocol version handling cleanup.

The protocol version is now represented the same way everywhere;
a 16-bit integer with the major (ie 3) in the high 8 bits, and
the minor in the low 8 bits.

Previously there was a mix between having a two element array,
and just keeping track of the minor.

Also strengthens the types of version variables in a few places.
SSL.Constants: Added fmt_version().

Added convenience function for formatting an SSL/TLS version number.
SSL.handshake: Use fmt_version().

Cleaned up a few debug messages.
Remove last traces of SSL2 support.
SSL.handshake: Use find_cert() on the client too.

find_cert() in the context object is now used to select suitable
client certificates in addition to server certificates.
Stronger type for random_string
Fixed a prototype mismatch
Replaced Yarrow with Fortuna. This implementation is about 35 times faster than the old one. The output has been verified against NIST statistical test suite 2.1.1.
Runtime: Fixed object type check in match_type_svalue().

The type checker function used by the variant dispatcher
checked object types in the wrong order, which caused it
to fail when called with objects implementing a superset
of the required object type.
Fixed a forgotten name change.
Resolve DSA in 7.8 mode as well.
Address fallout from stronger random type.